pair_mgpt.cpp
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Created: Tue, Feb 18, 23:51

pair_mgpt.cpp
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	/* ----------------------------------------------------------------------
	LAMMPS - Large-scale Atomic/Molecular Massively Parallel Simulator
	http://lammps.sandia.gov, Sandia National Laboratories
	Steve Plimpton, sjplimp@sandia.gov

	Copyright (2003) Sandia Corporation. Under the terms of Contract
	DE-AC04-94AL85000 with Sandia Corporation, the U.S. Government retains
	certain rights in this software. This software is distributed under
	the GNU General Public License.

	See the README file in the top-level LAMMPS directory.
	------------------------------------------------------------------------- */

	/* ----------------------------------------------------------------------
	Contributing authors: Tomas Oppelstrup, LLNL (oppelstrup2@llnl.gov)
	and John Moriarty, LLNL (moriarty2@llnl.gov)

	Fast MGPT algorithm developed by Tomas Oppelstrup (2015) based on the
	matrix MGPT v4.4 FORTRAN routine of John Moriarty (2006) as converted
	to C++ for LAMMPS application by Jamie Marian and Alexander Stukowski
	(2011). See LLNL copyright notice at bottom of this file.
	------------------------------------------------------------------------- */

	#include <cmath>
	#include <cstdio>
	#include <cstdlib>
	#include <cstring>
	#include <cassert>

	#include "pair_mgpt.h"
	#include "atom.h"
	#include "force.h"
	#include "comm.h"
	#include "memory.h"
	#include "neighbor.h"
	#include "neigh_list.h"
	#include "neigh_request.h"
	#include "memory.h"
	#include "error.h"


	using namespace LAMMPS_NS;

	//#define TIMING_ON

	#ifdef TIMING_ON
	#include <sys/time.h>
	#include <time.h>
	//#include "rdtsc.h"
	#ifdef __bgq__
	#include <hwi/include/bqc/A2_inlines.h>
	#endif

	static double gettime(int x = 0) {
	if(1) {
	/*
	struct timeval tv;
	gettimeofday(&tv,NULL);
	return tv.tv_sec + 1e-6 * tv.tv_usec;
	*/
	/*
	const double x = 1.0 / CLOCKS_PER_SEC;
	return clock() * x;
	*/

	//const double invfreq = 1.0 / 2394.108e6;
	/*
	const double invfreq = 1.0 / 700e6;
	unsigned long long int x = rdtsc();
	return x*invfreq;
	*/

	const double invfreq = 1.0 / 1.6e9;
	unsigned long long int x = GetTimeBase();
	return x*invfreq;


	} else
	return 0.0;
	}
	#else
	static double gettime(int x = 0) { return 0.0; }
	#endif


	/* ---------------------------------------------------------------------- */

	PairMGPT::PairMGPT(LAMMPS *lmp) : Pair(lmp)
	{
	single_enable = 0;
	one_coeff = 1;
	ghostneigh = 1;
	}

	PairMGPT::~PairMGPT()
	{
	if(allocated) {
	memory->destroy(setflag);
	memory->destroy(cutsq);
	memory->destroy(cutghost);
	}
	}

	/* ---------------------------------------------------------------------- */


	static double t_make_b2 = 0.0,n_make_b2 = 0.0;

	template<typename intype,typename outtype,int ni,int nj> void fmatconv(intype *array) {
	outtype cast = (outtype ) array;
	for(int i = 0; i<ni; i++)
	for(int j = 0; j<nj; j++)
	cast[inj+j] = array[inj+j];
	}

	void PairMGPT::make_bond(const double xx[][3],int i,int j,bond_data *bptr) {
	double rrij[3],rij;
	int p;

	double t0,t1;

	/* Check that alignment requirements for SIMD code are fullfilled */
	assert( (((unsigned long long int) (bptr->H.m )) & 31) == 0 );
	assert( (((unsigned long long int) (bptr->Hx.m)) & 31) == 0 );
	assert( (((unsigned long long int) (bptr->Hy.m)) & 31) == 0 );
	assert( (((unsigned long long int) (bptr->Hz.m)) & 31) == 0 );

	rij = 0.0;
	for(p = 0; p<3; p++) {
	rrij[p] = xx[i][p] - xx[j][p];
	rij = rij + rrij[p]*rrij[p];
	}

	/* Zero all matrix elements */
	for(i = 0; i<8; i++)
	for(j = 0; j<8; j++) {
	bptr->H.m[i][j] = 0.0;
	bptr->Hx.m[i][j] = 0.0;
	bptr->Hy.m[i][j] = 0.0;
	bptr->Hz.m[i][j] = 0.0;
	bptr->Hz.m[j][i] = 0.0;
	}

	if(rij <= rcrit*rcrit) {
	t0 = gettime();
	if(lang == 3) {
	hamltn_5_raw(rrij[0],rrij[1],rrij[2],
	bptr->H.m ,bptr->Hx.m,
	bptr->Hy.m,bptr->Hz.m,&bptr->fl_deriv_sum);
	} else {
	hamltn_7_raw(rrij[0],rrij[1],rrij[2],
	bptr->H.m ,bptr->Hx.m,
	bptr->Hy.m,bptr->Hz.m,&bptr->fl_deriv_sum);
	}

	t1 = gettime();
	t_make_b2 += t1-t0;
	n_make_b2++;
	} else {
	bptr->fl_deriv_sum = 0.0;
	}

	if(linalg.single) {
	fmatconv<double,float,7,8>(&(bptr->H.m[1][0]));
	fmatconv<double,float,7,8>(&(bptr->Hx.m[1][0]));
	fmatconv<double,float,7,8>(&(bptr->Hy.m[1][0]));
	fmatconv<double,float,7,8>(&(bptr->Hz.m[1][0]));
	}
	}

	static double t_trace = 0.0,n_trace = 0.0;
	/*
	static inline double mtrace(int n,double A[8][8],double B[8][8]) {
	double t0,t1;
	double s;

	t0 = gettime();
	if(n == 5) s = mtrace_5(A,B);
	else if(n == 7) s = mtrace_7(A,B);
	else {
	s = 0.0;
	for(int i = 1; i<=n; i++)
	for(int j = 1; j<=n; j++)
	s = s + A[i][j]*B[i][j];
	}
	t1 = gettime();
	t_trace += t1-t0;
	n_trace++;

	return s;
	}
	*/

	void PairMGPT::make_triplet(bond_data ij_bond,bond_data ik_bond,
	triplet_data *triptr) {
	if(1) {
	const trmul_fun tr_mul = linalg.tr_mul;
	tr_mul(&(ij_bond->H.m[1][0]), &(ik_bond->H.m[1][0]) ,&(triptr->H1H2.m[1][0]) );
	tr_mul(&(ij_bond->Hx.m[1][0]),&(ik_bond->H.m[1][0]) ,&(triptr->H1xH2.m[1][0]));
	tr_mul(&(ij_bond->Hy.m[1][0]),&(ik_bond->H.m[1][0]) ,&(triptr->H1yH2.m[1][0]));
	tr_mul(&(ij_bond->Hz.m[1][0]),&(ik_bond->H.m[1][0]) ,&(triptr->H1zH2.m[1][0]));
	tr_mul(&(ij_bond->H.m[1][0]) ,&(ik_bond->Hx.m[1][0]),&(triptr->H1H2x.m[1][0]));
	tr_mul(&(ij_bond->H.m[1][0]) ,&(ik_bond->Hy.m[1][0]),&(triptr->H1H2y.m[1][0]));
	tr_mul(&(ij_bond->H.m[1][0]) ,&(ik_bond->Hz.m[1][0]),&(triptr->H1H2z.m[1][0]));
	} else {
	transprod(ij_bond->H, ik_bond->H ,triptr->H1H2 );
	transprod(ij_bond->Hx,ik_bond->H ,triptr->H1xH2);
	transprod(ij_bond->Hy,ik_bond->H ,triptr->H1yH2);
	transprod(ij_bond->Hz,ik_bond->H ,triptr->H1zH2);
	transprod(ij_bond->H ,ik_bond->Hx,triptr->H1H2x);
	transprod(ij_bond->H ,ik_bond->Hy,triptr->H1H2y);
	transprod(ij_bond->H ,ik_bond->Hz,triptr->H1H2z);
	}
	}

	static double t_make_t = 0.0,t_make_b = 0.0,n_make = 0.0;

	PairMGPT::triplet_data *PairMGPT::get_triplet(const double xx[][3],int i,int j,int k,
	Hash<bond_data,Doublet> *bhash,
	triplet_data *twork,
	double dvir_ij_p,double dvir_ik_p) {
	const int recompute = 0;
	static bond_data bij_work,bik_work;

	double t0,t1;

	bond_data bij = 0,bik = 0;
	triplet_data *tptr = 0;

	t0 = gettime();
	if(recompute == 0) {
	bij = bhash->Lookup(Doublet(i,j));
	bik = bhash->Lookup(Doublet(i,k));
	}

	if(bij == 0) {
	if(recompute == 0)
	bij = bhash->Insert(Doublet(i,j));
	else
	bij = &bij_work;
	if(i < j)
	make_bond(xx,i,j,bij);
	else
	make_bond(xx,j,i,bij);
	}

	if(bik == 0) {
	if(recompute == 0)
	bik = bhash->Insert(Doublet(i,k));
	else
	bik = &bik_work;
	if(i < k)
	make_bond(xx,i,k,bik);
	else
	make_bond(xx,k,i,bik);
	}
	t1 = gettime();
	t_make_b += t1-t0;

	t0 = gettime();
	if(bij != 0 && bij != 0) {
	tptr = twork;
	make_triplet(bij,bik,tptr);
	*dvir_ij_p = bij->fl_deriv_sum;
	*dvir_ik_p = bik->fl_deriv_sum;
	} else {
	*dvir_ij_p = 0.0;
	*dvir_ik_p = 0.0;
	}
	t1 = gettime();
	t_make_t += t1-t0;
	n_make++;
	return tptr;
	}


	double PairMGPT::numderiv3t(double xx[][3],int i,int j,int k,int p) {
	static bond_data Bij,Bjk,Bki;
	const double delta = 1e-5;

	const double xsave = xx[i][p];
	double e1,e2;

	const double vc = splinepot.vc;

	xx[i][p] = xsave + delta;
	make_bond(xx,i,j,&Bij);
	make_bond(xx,j,k,&Bjk);
	make_bond(xx,k,i,&Bki);
	e1 = trace(prodmat(Bij.H,Bjk.H),Bki.H) * (vc/anorm3);

	xx[i][p] = xsave - delta;
	make_bond(xx,i,j,&Bij);
	if(0) { /* This bond doesn't change when i is perturbed */
	make_bond(xx,j,k,&Bjk);
	}
	make_bond(xx,k,i,&Bki);
	e2 = trace(prodmat(Bij.H,Bjk.H),Bki.H) * (vc/anorm3);

	xx[i][p] = xsave;
	return (e1 - e2)/(2.0*delta);
	}

	double PairMGPT::numderiv3v(double xx[][3],int i,int j,int k,int p,int ipert) {
	static bond_data Bij,Bik;
	const double delta = 1e-5;

	const double xsave = xx[ipert][p];
	double e1,e2;

	const double vd = splinepot.vd;

	xx[ipert][p] = xsave + delta;
	make_bond(xx,i,j,&Bij);
	make_bond(xx,i,k,&Bik);
	e1 = trace(prodmat(Bij.H,Bij.H),prodmat(Bik.H,Bik.H)) * (vd/anorm4);

	xx[ipert][p] = xsave - delta;
	make_bond(xx,i,j,&Bij);
	make_bond(xx,i,k,&Bik);
	e2 = trace(prodmat(Bij.H,Bij.H),prodmat(Bik.H,Bik.H)) * (vd/anorm4);

	xx[ipert][p] = xsave;
	return (e1 - e2)/(2.0*delta);
	}


	double PairMGPT::numderiv4(double xx[][3],int i,int j,int k,int m,int p) {
	static bond_data Bij,Bjk,Bkm,Bmi;
	const double delta = 1e-5;

	const double xsave = xx[i][p];
	double e1,e2;

	const double ve = splinepot.ve;

	xx[i][p] = xsave + delta;
	make_bond(xx,i,j,&Bij);
	make_bond(xx,j,k,&Bjk);
	make_bond(xx,k,m,&Bkm);
	make_bond(xx,m,i,&Bmi);
	e1 = trace(prodmat(Bij.H,Bjk.H),prodmat(Bkm.H,Bmi.H)) * (ve/anorm4);

	xx[i][p] = xsave - delta;
	make_bond(xx,i,j,&Bij);
	if(0) { /* Only the i coordinates changed... */
	make_bond(xx,j,k,&Bjk);
	make_bond(xx,k,m,&Bkm);
	}
	make_bond(xx,m,i,&Bmi);
	e2 = trace(prodmat(Bij.H,Bjk.H),prodmat(Bkm.H,Bmi.H)) * (ve/anorm4);

	xx[i][p] = xsave;
	return (e1 - e2)/(2.0*delta);
	}

	static double dtol = 1e-6;
	void PairMGPT::force_debug_3t(double xx[][3],
	int i0,int j0,int k0,
	int i ,int j ,int k ,
	double dfix,double dfiy,double dfiz,
	double dfjx,double dfjy,double dfjz,
	double dfkx,double dfky,double dfkz) {
	double dfi[3],dfj[3],dfk[3];
	dfi[0] = dfix; dfi[1] = dfiy; dfi[2] = dfiz;
	dfj[0] = dfjx; dfj[1] = dfjy; dfj[2] = dfjz;
	dfk[0] = dfkx; dfk[1] = dfky; dfk[2] = dfkz;

	for(int p = 0; p<3; p++) {
	/* Compute numerical derivatives by displacing atoms i,j,k */
	double ndfi,ndfj,ndfk;
	ndfi = -numderiv3t(xx,i,j,k,p);
	ndfj = -numderiv3t(xx,j,k,i,p);
	ndfk = -numderiv3t(xx,k,i,j,p);

	if((fabs(dfi[p] - ndfi) > dtol &&
	fabs(dfi[p] - ndfi) > dtol*fabs(ndfi)) \|\|
	(fabs(dfj[p] - ndfj) > dtol &&
	fabs(dfj[p] - ndfj) > dtol*fabs(ndfj)) \|\|
	(fabs(dfk[p] - ndfk) > dtol &&
	fabs(dfk[p] - ndfk) > dtol*fabs(ndfk))) {
	printf("Force error in T12 & T23 & T31 :: i,j,k = %d,%d,%d\n",i0,j0,k0);
	printf(" dE/d%c[i] = %20.10e %20.10e\n", 'x'+p,ndfi, dfi[p]);
	printf(" dE/d%c[j] = %20.10e %20.10e\n", 'x'+p,ndfj, dfj[p]);
	printf(" dE/d%c[k] = %20.10e %20.10e\n", 'x'+p,ndfk, dfk[p]);
	printf("\n");
	}
	}
	}

	void PairMGPT::force_debug_3v(double xx[][3],
	int i0,int j0,int k0,
	int i ,int j ,int k ,
	double dfix,double dfiy,double dfiz,
	double dfjx,double dfjy,double dfjz,
	double dfkx,double dfky,double dfkz) {
	double dfi[3],dfj[3],dfk[3];
	dfi[0] = dfix; dfi[1] = dfiy; dfi[2] = dfiz;
	dfj[0] = dfjx; dfj[1] = dfjy; dfj[2] = dfjz;
	dfk[0] = dfkx; dfk[1] = dfky; dfk[2] = dfkz;

	for(int p = 0; p<3; p++) {
	/* Compute numerical derivatives by displacing atoms i,j,k */
	double ndfi,ndfj,ndfk;
	ndfi = -numderiv3v(xx,i,j,k,p,i0);
	ndfj = -numderiv3v(xx,i,j,k,p,j0);
	ndfk = -numderiv3v(xx,i,j,k,p,k0);

	if((fabs(dfi[p] - ndfi) > dtol &&
	fabs(dfi[p] - ndfi) > dtol*fabs(ndfi)) \|\|
	(fabs(dfj[p] - ndfj) > dtol &&
	fabs(dfj[p] - ndfj) > dtol*fabs(ndfj)) \|\|
	(fabs(dfk[p] - ndfk) > dtol &&
	fabs(dfk[p] - ndfk) > dtol*fabs(ndfk))) {
	printf("Force error in T12 :: i,j,k = %d,%d,%d\n",i0,j0,k0);
	printf(" dE/d%c[i] = %20.10e %20.10e\n", 'x'+p,ndfi, dfi[p]);
	printf(" dE/d%c[j] = %20.10e %20.10e\n", 'x'+p,ndfj, dfj[p]);
	printf(" dE/d%c[k] = %20.10e %20.10e\n", 'x'+p,ndfk, dfk[p]);
	printf("\n");
	}
	}
	}

	void PairMGPT::force_debug_4(double xx[][3],
	int i0,int j0,int k0,int m0,
	int i ,int j ,int k ,int m ,
	double dfix,double dfiy,double dfiz,
	double dfjx,double dfjy,double dfjz,
	double dfkx,double dfky,double dfkz,
	double dfmx,double dfmy,double dfmz) {

	double dfi[3],dfj[3],dfk[3],dfm[3];
	dfi[0] = dfix; dfi[1] = dfiy; dfi[2] = dfiz;
	dfj[0] = dfjx; dfj[1] = dfjy; dfj[2] = dfjz;
	dfk[0] = dfkx; dfk[1] = dfky; dfk[2] = dfkz;
	dfm[0] = dfmx; dfm[1] = dfmy; dfm[2] = dfmz;

	const int ii0[] = {i0,j0,k0,m0},ii[] = {i,j,k,m,i,j,k};

	for(int p = 0; p<3; p++) {
	/* Compute numerical derivatives by displacing atoms i,j,k,m */
	double ndfi,ndfj,ndfk,ndfm;
	if(1) {
	double ndf[] = {0.0,0.0,0.0,0.0};
	for(int s = 0; s<4; s++)
	for(int t = 0; t<4; t++)
	if(ii[s] == ii0[t])
	ndf[t] = -numderiv4(xx,ii[s],ii[s+1],ii[s+2],ii[s+3],p);
	ndfi = ndf[0]; ndfj = ndf[1];
	ndfk = ndf[2]; ndfm = ndf[3];
	} else {
	ndfi = -numderiv4(xx,i,j,k,m,p);
	ndfj = -numderiv4(xx,j,k,m,i,p);
	ndfk = -numderiv4(xx,k,m,i,j,p);
	ndfm = -numderiv4(xx,m,i,j,k,p);
	}

	if((fabs(dfi[p] - ndfi) > dtol &&
	fabs(dfi[p] - ndfi) > dtol*fabs(ndfi)) \|\|
	(fabs(dfj[p] - ndfj) > dtol &&
	fabs(dfj[p] - ndfj) > dtol*fabs(ndfj)) \|\|
	(fabs(dfk[p] - ndfk) > dtol &&
	fabs(dfk[p] - ndfk) > dtol*fabs(ndfk)) \|\|
	(fabs(dfm[p] - ndfm) > dtol &&
	fabs(dfm[p] - ndfm) > dtol*fabs(ndfm))) {
	printf("Force error in T31 & T64 :: i,j,k,m = %d,%d,%d,%d\n",i0,j0,k0,m0);
	printf(" dE/d%c[i] = %20.10e %20.10e\n", 'x'+p,ndfi, dfi[p]);
	printf(" dE/d%c[j] = %20.10e %20.10e\n", 'x'+p,ndfj, dfj[p]);
	printf(" dE/d%c[k] = %20.10e %20.10e\n", 'x'+p,ndfk, dfk[p]);
	printf(" dE/d%c[m] = %20.10e %20.10e\n", 'x'+p,ndfm, dfm[p]);
	printf("\n");
	}
	}
	}



	/*
	#define trd_update_4(T12,T45,coord) \
	do { \
	trd1 = transtrace(T12->H1##coord##H2,T45->H1H2 ); \
	trd2 = transtrace(T12->H1H2##coord,T45->H1H2 ); \
	trd3 = transtrace(T12->H1H2 ,T45->H1##coord##H2); \
	trd4 = transtrace(T12->H1H2 ,T45->H1H2##coord ); \
	} while(0)
	*/
	#define trd_update_4(T12,T45) \
	do { \
	tr_trace3(&(T45->H1H2.m[1][0]), \
	&(T12->H1xH2.m[1][0]),&utr1x.d, \
	&(T12->H1yH2.m[1][0]),&utr1y.d, \
	&(T12->H1zH2.m[1][0]),&utr1z.d); \
	tr_trace3(&(T45->H1H2.m[1][0]), \
	&(T12->H1H2x.m[1][0]),&utr2x.d, \
	&(T12->H1H2y.m[1][0]),&utr2y.d, \
	&(T12->H1H2z.m[1][0]),&utr2z.d); \
	tr_trace3(&(T12->H1H2.m[1][0]), \
	&(T45->H1xH2.m[1][0]),&utr3x.d, \
	&(T45->H1yH2.m[1][0]),&utr3y.d, \
	&(T45->H1zH2.m[1][0]),&utr3z.d); \
	tr_trace3(&(T12->H1H2.m[1][0]), \
	&(T45->H1H2x.m[1][0]),&utr4x.d, \
	&(T45->H1H2y.m[1][0]),&utr4y.d, \
	&(T45->H1H2z.m[1][0]),&utr4z.d); \
	if(linalg.single) { \
	trd1x = utr1x.f; trd2x = utr2x.f; trd3x = utr3x.f; trd4x = utr4x.f; \
	trd1y = utr1y.f; trd2y = utr2y.f; trd3y = utr3y.f; trd4y = utr4y.f; \
	trd1z = utr1z.f; trd2z = utr2z.f; trd3z = utr3z.f; trd4z = utr4z.f; \
	} else { \
	trd1x = utr1x.d; trd2x = utr2x.d; trd3x = utr3x.d; trd4x = utr4x.d; \
	trd1y = utr1y.d; trd2y = utr2y.d; trd3y = utr3y.d; trd4y = utr4y.d; \
	trd1z = utr1z.d; trd2z = utr2z.d; trd3z = utr3z.d; trd4z = utr4z.d; \
	} \
	} while(0)

	#define dfix_update_4a(coord) \
	do { \
	dfi##coord = ( (-sij)trd1##coord + (-sim)trd3##coord ) * (ve / anorm4); \
	dfj##coord = ( ( sij)trd1##coord + (-sjk)trd2##coord ) * (ve / anorm4); \
	dfk##coord = ( ( sjk)trd2##coord + (-skm)trd4##coord ) * (ve / anorm4); \
	dfm##coord = ( ( sim)trd3##coord + ( skm)trd4##coord ) * (ve / anorm4); \
	} while(0)


	#define dfix_update_4b(coord) \
	do { \
	dfi##coord = ( ( ski)trd1##coord + (-sim)trd3##coord ) * (ve / anorm4); \
	dfj##coord = ( (-sjk)trd2##coord + (-sjm)trd4##coord ) * (ve / anorm4); \
	dfk##coord = ( (-ski)trd1##coord + ( sjk)trd2##coord ) * (ve / anorm4); \
	dfm##coord = ( ( sim)trd3##coord + ( sjm)trd4##coord ) * (ve / anorm4); \
	} while(0);

	#define dfix_update_4c(coord) \
	do { \
	dfi##coord = ( (-sij)trd1##coord + ( ski)trd2##coord ) * (ve / anorm4); \
	dfj##coord = ( ( sij)trd1##coord + (-sjm)trd3##coord ) * (ve / anorm4); \
	dfk##coord = ( (-ski)trd2##coord + (-skm)trd4##coord ) * (ve / anorm4); \
	dfm##coord = ( ( sjm)trd3##coord + ( skm)trd4##coord ) * (ve / anorm4); \
	} while(0);

	#define accumulate_forces_2(w) \
	do { \
	fix = fix + dfix*(w); \
	fiy = fiy + dfiy*(w); \
	fiz = fiz + dfiz*(w); \
	\
	fjx = fjx + dfjx*(w); \
	fjy = fjy + dfjy*(w); \
	fjz = fjz + dfjz*(w); \
	} while(0)

	#define accumulate_forces_3(w) \
	do { \
	accumulate_forces_2(w); \
	fkx = fkx + dfkx*(w); \
	fky = fky + dfky*(w); \
	fkz = fkz + dfkz*(w); \
	} while(0)

	#define accumulate_forces_4(w) \
	do { \
	accumulate_forces_3(w); \
	fmx = fmx + dfmx*(w); \
	fmy = fmy + dfmy*(w); \
	fmz = fmz + dfmz*(w); \
	} while(0)



	#define restrict __restrict__
	#ifdef __bg__
	#define const
	#endif
	static int ntr_calls = 0;
	static trtrace3_fun tr_internal;
	static void tr_count(const double * restrict A,
	const double * restrict B1,double * restrict t1,
	const double * restrict B2,double * restrict t2,
	const double * restrict B3,double * restrict t3) {
	tr_internal(A,B1,t1,B2,t2,B3,t3);
	ntr_calls++;
	}
	#ifdef __bg__
	#undef const
	#endif
	#undef restrict


	int PairMGPT::Matrix::sz;
	void PairMGPT::compute_x(const int nnei,const int const *nlist,
	double e_s,double e_p,double e_t,double e_q,
	int evflag,int newton_pair) {
	Hash<bond_data,Doublet> bond_hash(100000);
	int i,j,k,m,ix,jx,kx,mx,itag,jtag,p;

	double e_single,e_pair,e_triplet,e_triplet_c,e_quad;
	double volvir2;

	double nbc = 0.0,tbl = 0.0,tbm = 0.0;
	const int lmax_local = lmax;

	//if(evflag) printf("##### ev flag is set... wasting cycles...\n");

	*e_s = -99.0;
	*e_p = -99.0;
	*e_t = -99.0;
	*e_q = -99.0;

	double t0,t1;

	t0 = gettime(1);
	e_single = e_pair = e_triplet = e_triplet_c = e_quad = 0.0;
	volvir2 = 0.0;

	t_make_t = t_make_b = t_make_b2 = t_trace = 0.0;
	n_make = n_make_b2 = n_trace = 0.0;

	double tx0,tx1,tsort = 0.0,tpair = 0.0,tlookup = 0.0;
	double ttriplet = 0.0,tquad = 0.0,tmem = 0.0;
	double ntsort = 0.0,ntpair = 0.0,ntlookup = 0.0;
	double nttriplet = 0.0,ntquad = 0.0,ntmem = 0.0,ntquaditer = 0.0;
	double mcount = 0.0,mcount2 = 0.0, qcount = 0.0;

	double fix,fjx,fkx,fmx,dfix,dfjx,dfkx,dfmx;
	double fiy,fjy,fky,fmy,dfiy,dfjy,dfky,dfmy;
	double fiz,fjz,fkz,fmz,dfiz,dfjz,dfkz,dfmz;

	double fsave[4][3] = { {0.0} } /* {{0.0}} is to get rid of uninitialized use warning */;

	//const int numerical_pair_forces = (nbody_flag/16)%2;
	const int pair_forces = (nbody_flag/2)%2,three_body_forces = (nbody_flag/4)%2,four_body_forces = (nbody_flag/8)%2;
	const int pair_energies = (nbody_flag/2)%2,three_body_energies = (nbody_flag/4)%2,four_body_energies = (nbody_flag/8)%2;
	const int single_energies = nbody_flag%2;

	const int triplet_debug = 0,quad_debug = 0;

	/* Energy and force scale factor for unit conversion. */
	const double e_scale = 0.5;

	#ifdef NEIGHMASK
	#define NIDX(x) (x)
	#else
	#define NIDX(x) ((x) & NEIGHMASK)
	#endif

	int nneitot,first,nlist_short;
	double w2,w3,w4;
	triplet_data T12work,T23work,T31work,T45work,T56work,T64work;
	triplet_data T12,T23,T31,T45,T56,T64;
	int c_ij,c_jk,c_ki,c_im,c_jm,c_km;
	int mi,mj,mk;
	double tr0,tr1,tr2,tr3;
	double v33,v43;
	double rcut2_pair = rmaxrmax,rcut2_bond = rcritrcrit,rij2;
	int ntot,nloc;

	double dvir_ij,dvir_jk,dvir_ki,dvir_im,dvir_jm,dvir_km;
	double vir3t = 0.0,vir3v = 0.0,vir4 = 0.0;

	double (xx)[3],(ff)[3],(*ss)[3];

	#ifdef TIMING_ON
	tr_internal = linalg.tr_trace; ntr_calls = 0;
	const trtrace3_fun tr_trace3 = tr_count;
	#else
	const trtrace3_fun tr_trace3 = linalg.tr_trace;
	#endif
	union {
	double d;
	float f;
	} utr1x,utr2x,utr3x,utr4x,utr1y,utr2y,utr3y,utr4y,utr1z,utr2z,utr3z,utr4z;
	double trd1x,trd2x,trd3x,trd4x;
	double trd1y,trd2y,trd3y,trd4y;
	double trd1z,trd2z,trd3z,trd4z;


	tx0 = gettime();

	double rhoinv;
	{
	double vtot = 1.0;
	double ntot = atom->natoms;
	for(i = 0; i<3; i++)
	vtot = vtot * (domain->boxhi[i] - domain->boxlo[i]);
	rhoinv = vtot / ntot;
	}

	/* Make sure triplet data work area is aligned and zeroed out. */ {
	assert(T12work.align_check() == 0);
	assert(T23work.align_check() == 0);
	assert(T31work.align_check() == 0);
	assert(T45work.align_check() == 0);
	assert(T56work.align_check() == 0);
	assert(T64work.align_check() == 0);

	T12work.zero(); T23work.zero(); T31work.zero();
	T45work.zero(); T56work.zero(); T64work.zero();
	}

	ntot = atom->nlocal + atom->nghost;
	nloc = atom->nlocal;
	//printf("[%3d] Allocating local array, size is %d atoms...\n",comm->me,j);
	xx = (double ()[3]) memory->smalloc(sizeof(double [3]) ntot,"mgpt: local position vector.");
	ff = (double ()[3]) memory->smalloc(sizeof(double [3]) ntot,"mgpt: local force vector.");
	//printf("[%3d] Initializing arrays...\n",comm->me);

	const int triclinic = domain->triclinic;
	double alpha[3] = {0.0,0.0,0.0};
	if(triclinic) {
	double E[3][3],EX[3][3];
	int cyc[] = {0,1,2,0,1};

	ss = (double ()[3]) memory->smalloc(sizeof(double [3]) ntot,
	"mgpt: local reduced coordinate vector.");

	for(i = 0; i<3; i++) {
	for(j = 0; j<3; j++)
	E[i][j] = 0.0;
	E[i][i] = domain->subhi_lamda[i] - domain->sublo_lamda[i];
	domain->lamda2x(E[i],EX[i]);
	}
	for(i = 0; i<3; i++) {
	int i1 = cyc[i+1],i2 = cyc[i+2];
	double dot = 0.0,ns2 = 0.0;
	for(j = 0; j<3; j++) {
	int j1 = cyc[j+1],j2 = cyc[j+2];
	double cj = EX[i1][j1]EX[i2][j2] - EX[i1][j2]EX[i2][j1];
	ns2 = ns2 + cj*cj;
	dot = dot + EX[i][j]*cj;
	}
	alpha[i] = E[i][i] / (dot/sqrt(ns2));
	if(comm->me == 0) {
	static int count = 0;
	if(count < 3)
	printf("@@@ alpha(%d) = %15.5e\n",i+1,alpha[i]);
	count++;
	}
	if(alpha[i] < 0.0) alpha[i] = -alpha[i];
	}
	} else
	ss = xx;

	nneitot = 0;
	for(ix = 0; ix<ntot; ix++) {
	for(p = 0; p<3; p++) {
	xx[ix][p] = atom->x[ix][p];
	ff[ix][p] = 0.0;
	}
	if(triclinic)
	domain->x2lamda(xx[ix],ss[ix]);
	nneitot = nneitot + nnei[ix];
	}

	first = (int ) memory->smalloc(sizeof(int) (ntot+1),"mgpt: first");
	nlist_short = (int ) memory->smalloc(sizeof(int) nneitot,"mgpt: nlist_short");

	tx1 = gettime();
	tmem += tx1-tx0;
	ntmem++;

	//printf("[%3d] Starting calculation...\n",comm->me);


	fix = fjx = fkx = fmx = 0.0;
	fiy = fjy = fky = fmy = 0.0;
	fiz = fjz = fkz = fmz = 0.0;

	int c_p = 0, c_t = 0, c_q = 0;

	if(0)
	if(domain->triclinic) {
	if(comm->me == 0)
	printf("Can not handle triclinic box yet\n");
	error->all(__FILE__,__LINE__,"Can not handle triclinic cell with mgpt yet.");
	}

	/*
	for(i = 0; i<nloc; i++) {
	printf("Atom %3d:: %10.3f %10.3f %10.3f\n",
	i,xx[i][0],xx[i][1],xx[i][2]);
	}
	*/

	first[0] = 0;
	for(i = 0; i<ntot; i++) {
	fix = fiy = fiz = 0.0;

	first[i+1] = first[i];

	const int c1 = c1_outside(ss[i],triclinic,alpha);

	tx0 = gettime();
	for(jx = 0; jx<nnei[i]; jx++) {
	fjx = fjy = fjz = 0.0;

	j = NIDX( nlist[i][jx] );

	rij2 = 0.0;
	for(p = 0; p<3; p++) {
	double t = xx[i][p] - xx[j][p];
	rij2 = rij2 + t*t;
	}

	if(c1 == 0 && rij2 < rcut2_pair) {
	if(j < i) {
	w2 = get_weight(triclinic,ss[i],ss[j]);

	if(w2 > 0.0) {
	/*
	Compute pair energy/force
	*/
	double de_pair,df,rij = sqrt(rij2);
	splinepot.eval_pot(rij,&de_pair,&df);
	de_pair = de_pair * e_scale * w2;
	df = df / rij * w2;


	if(pair_energies == 0) de_pair = 0.0;
	e_pair = e_pair + de_pair;
	c_p++;

	if(pair_forces == 0) df = 0.0;

	if(volpres_flag && pair_energies) {
	double dvir;
	splinepot.eval_vir(rij,&dvir);
	volvir2 = volvir2 - dvir * w2;

	/* Per-atom virial contribution of volumetric energy term */
	if(vflag_atom)
	for(int pp = 0; pp<3; pp++) {
	//virial[i] = virial[i] + rhoinve_scalevolvir2;
	vatom[i][pp] -= 0.5 * rhoinve_scaledvir*w2;
	vatom[j][pp] -= 0.5 * rhoinve_scaledvir*w2;
	}
	}

	double drijx = xx[j][0] - xx[i][0];
	double drijy = xx[j][1] - xx[i][1];
	double drijz = xx[j][2] - xx[i][2];

	fix = fix + df*drijx;
	fjx = fjx - df*drijx;

	fiy = fiy + df*drijy;
	fjy = fjy - df*drijy;

	fiz = fiz + df*drijz;
	fjz = fjz - df*drijz;

	if(evflag) {
	//ev_tally(i,j,nloc,newton_pair,de_pair,0.0,df,-drijx,-drijy,-drijz);
	/* To fix stress-per-atom scaling, and sign */
	ev_tally(i,j,nloc,newton_pair,de_pair,0.0,-df * e_scale,-drijx,-drijy,-drijz);
	}

	ff[j][0] += fjx * e_scale;
	ff[j][1] += fjy * e_scale;
	ff[j][2] += fjz * e_scale;

	}
	}
	}

	if(rij2 < rcut2_bond && c2_outside(ss[i],ss[j],triclinic,alpha) == 0) {
	/*
	Add j to short neighbor list for i.
	Insert j to keep list sorted.
	*/

	p = first[i+1]-1;
	while(p >= first[i] && nlist_short[p] > j) {
	nlist_short[p+1] = nlist_short[p];
	p = p - 1;
	}
	nlist_short[p+1] = j;
	first[i+1] = first[i+1] + 1;
	if(first[i+1] > nneitot) {
	printf("nneitot = %d, short list full. i=%d\n",
	nneitot,i);
	error->one(__FILE__,__LINE__,"Shit! Short list full\n");
	}

	}
	}

	ff[i][0] += fix * e_scale;
	ff[i][1] += fiy * e_scale;
	ff[i][2] += fiz * e_scale;

	tx1 = gettime();
	tpair += tx1-tx0;
	ntpair += nnei[i];
	}

	for(i = 0; i<ntot; i++) {
	fix = fiy = fiz = 0.0;

	/*
	Use short lists for triplets and quadruplets.
	For open (2-bonded) triplets, can only use k<j, but not k<i.
	For closed (3-bonded) triplets, we can assume k<j<i.

	Quadruplets:
	Always use k<j<i, and require m<i.
	If 5-bonded with im bond, ignore the quadruplet.
	If 6-bonded, require m<k.

	For 4-bonded quadruplets, we can still use k<j, but also
	assume max(m,j)<i
	*/

	if(three_body_energies \|\| three_body_forces \|\|
	four_body_energies \|\| four_body_forces)
	for(jx = first[i]; jx<first[i+1]; jx++) {
	fjx = fjy = fjz = 0.0;

	j = nlist_short[jx];

	for(kx = first[i]; kx<jx; kx++) {
	fkx = fky = fkz = 0.0;

	k = nlist_short[kx];

	/*
	Search lists of j and k, and see if
	1) j is in k-list (closed triplet)
	2) j and k have a common neighbor (closed quadruplet)
	*/

	c_ij = c_ki = 1;

	const int sij = (i < j) ? 1 : -1;
	const int sjk = (j < k) ? 1 : -1;
	const int ski = (k < i) ? 1 : -1;


	T12 = T23 = T31 = 0;

	mj = first[j];
	/*
	Since i is in the j-list, and i > k and the list
	is sorted, the loop below terminates:-)
	*/
	while(mj < first[j+1] && nlist_short[mj] < k) mj = mj + 1;
	if(mj < first[j+1] && nlist_short[mj] == k) {
	/* Closed triplet */
	c_jk = 1;

	if(j > i) continue; /* Require k<j<i for closed triplets */
	} else {
	/* Open triplet */
	c_jk = 0;
	}

	tx0 = gettime();

	w3 = get_weight(triclinic,ss[i],ss[j],ss[k]);

	int triplet_defer;
	if(w3 > 0.0) {
	triplet_defer = 0;

	dvir_ij = dvir_jk = dvir_ki = 0.0;
	if(c_ij && c_jk)
	T12 = get_triplet(xx,j,i,k,&bond_hash,&T12work,&dvir_ij,&dvir_jk);
	if(c_ki && c_jk)
	T23 = get_triplet(xx,k,i,j,&bond_hash,&T23work,&dvir_ki,&dvir_jk);
	if(c_ij && c_ki)
	T31 = get_triplet(xx,i,j,k,&bond_hash,&T31work,&dvir_ij,&dvir_ki);

	if(evflag) {
	fsave[0][0] = fix; fsave[0][1] = fiy; fsave[0][2] = fiz;
	fsave[1][0] = fjx; fsave[1][1] = fjy; fsave[1][2] = fjz;
	fsave[2][0] = fkx; fsave[2][1] = fky; fsave[2][2] = fkz;
	fix = fiy = fiz = 0.0;
	fjx = fjy = fjz = 0.0;
	fkx = fky = fkz = 0.0;
	}

	tr0 = tr1 = tr2 = tr3 = 0.0;
	double xvir3t,xvir3v;
	xvir3t = xvir3v = 0.0;

	if(T12 && T23) {
	bond_data *bki = bond_hash.Lookup(Doublet(k,i));

	if(three_body_energies && evflag) {
	tr0 = transtrace(T12->H1H2,bki->H);
	double dvir = ((dvir_ij + dvir_jk + bki->fl_deriv_sum)*splinepot.vc +
	splinepot.dvc)tr0w3/anorm3;
	vir3t = vir3t + dvir;
	xvir3t = xvir3t + dvir;
	}
	mcount2++;

	{
	const double vc = splinepot.vc;
	tr_trace3(&(bki->H.m[1][0]),
	&(T12->H1xH2.m[1][0]),&utr1x.d,
	&(T12->H1yH2.m[1][0]),&utr1y.d,
	&(T12->H1zH2.m[1][0]),&utr1z.d);

	tr_trace3(&(bki->H.m[1][0]),
	&(T12->H1H2x.m[1][0]),&utr2x.d,
	&(T12->H1H2y.m[1][0]),&utr2y.d,
	&(T12->H1H2z.m[1][0]),&utr2z.d);

	tr_trace3(&(T12->H1H2.m[1][0]),
	&(bki->Hx.m[1][0]),&utr3x.d,
	&(bki->Hy.m[1][0]),&utr3y.d,
	&(bki->Hz.m[1][0]),&utr3z.d);

	if(linalg.single) {
	trd1x = utr1x.f; trd2x = utr2x.f; trd3x = utr3x.f;
	trd1y = utr1y.f; trd2y = utr2y.f; trd3y = utr3y.f;
	trd1z = utr1z.f; trd2z = utr2z.f; trd3z = utr3z.f;
	} else {
	trd1x = utr1x.d; trd2x = utr2x.d; trd3x = utr3x.d;
	trd1y = utr1y.d; trd2y = utr2y.d; trd3y = utr3y.d;
	trd1z = utr1z.d; trd2z = utr2z.d; trd3z = utr3z.d;
	}

	dfix = ( (-sij)trd1x + ( ski)trd3x ) * (vc / anorm3);
	dfjx = ( ( sij)trd1x + (-sjk)trd2x ) * (vc / anorm3);
	dfkx = ( ( sjk)trd2x + (-ski)trd3x ) * (vc / anorm3);

	dfiy = ( (-sij)trd1y + ( ski)trd3y ) * (vc / anorm3);
	dfjy = ( ( sij)trd1y + (-sjk)trd2y ) * (vc / anorm3);
	dfky = ( ( sjk)trd2y + (-ski)trd3y ) * (vc / anorm3);

	dfiz = ( (-sij)trd1z + ( ski)trd3z ) * (vc / anorm3);
	dfjz = ( ( sij)trd1z + (-sjk)trd2z ) * (vc / anorm3);
	dfkz = ( ( sjk)trd2z + (-ski)trd3z ) * (vc / anorm3);
	}

	if(triplet_debug)
	force_debug_3t(xx,i,j,k, i,j,k,
	dfix,dfiy,dfiz,
	dfjx,dfjy,dfjz,
	dfkx,dfky,dfkz);

	if(three_body_forces)
	accumulate_forces_3(w3);
	}

	if(T12 != 0) {
	//printf("T12 i,j,k = %d,%d,%d\n",i,j,k);
	mcount++;
	if(three_body_energies && evflag) {
	tr1 = transtrace(T12->H1H2,T12->H1H2);
	double dvir = (2.0(dvir_ij + dvir_jk)splinepot.vd +
	splinepot.dvd)tr1w3/anorm4;
	vir3v = vir3v + dvir;
	xvir3v = xvir3v + dvir;
	}

	{
	const double vd = splinepot.vd;

	tr_trace3(&(T12->H1H2.m[1][0]),
	&(T12->H1xH2.m[1][0]),&utr1x.d,
	&(T12->H1yH2.m[1][0]),&utr1y.d,
	&(T12->H1zH2.m[1][0]),&utr1z.d);
	tr_trace3(&(T12->H1H2.m[1][0]),
	&(T12->H1H2x.m[1][0]),&utr2x.d,
	&(T12->H1H2y.m[1][0]),&utr2y.d,
	&(T12->H1H2z.m[1][0]),&utr2z.d);
	if(linalg.single) {
	trd1x = utr1x.f; trd2x = utr2x.f;
	trd1y = utr1y.f; trd2y = utr2y.f;
	trd1z = utr1z.f; trd2z = utr2z.f;
	} else {
	trd1x = utr1x.d; trd2x = utr2x.d;
	trd1y = utr1y.d; trd2y = utr2y.d;
	trd1z = utr1z.d; trd2z = utr2z.d;
	}

	dfix = 2.0(-sij)trd1x * (vd / anorm4);
	dfkx = 2.0( sjk)trd2x * (vd / anorm4);
	dfjx = -(dfix + dfkx);

	dfiy = 2.0(-sij)trd1y * (vd / anorm4);
	dfky = 2.0( sjk)trd2y * (vd / anorm4);
	dfjy = -(dfiy + dfky);

	dfiz = 2.0(-sij)trd1z * (vd / anorm4);
	dfkz = 2.0( sjk)trd2z * (vd / anorm4);
	dfjz = -(dfiz + dfkz);
	}

	if(triplet_debug) /* Compare forces to numerical derivatives */
	force_debug_3v(xx,i,j,k, j,i,k,
	dfix,dfiy,dfiz,
	dfjx,dfjy,dfjz,
	dfkx,dfky,dfkz);


	if(three_body_forces)
	accumulate_forces_3(w3);
	}

	if(T23 != 0) {
	//printf("T23 i,j,k = %d,%d,%d\n",i,j,k);
	mcount++;
	if(three_body_energies && evflag) {
	tr2 = transtrace(T23->H1H2,T23->H1H2);
	double dvir = (2.0(dvir_jk + dvir_ki)splinepot.vd +
	splinepot.dvd)tr2w3/anorm4;
	vir3v = vir3v + dvir;
	xvir3v = xvir3v + dvir;
	}

	{
	const double vd = splinepot.vd;

	tr_trace3(&(T23->H1H2.m[1][0]),
	&(T23->H1xH2.m[1][0]),&utr1x.d,
	&(T23->H1yH2.m[1][0]),&utr1y.d,
	&(T23->H1zH2.m[1][0]),&utr1z.d);
	tr_trace3(&(T23->H1H2.m[1][0]),
	&(T23->H1H2x.m[1][0]),&utr2x.d,
	&(T23->H1H2y.m[1][0]),&utr2y.d,
	&(T23->H1H2z.m[1][0]),&utr2z.d);
	if(linalg.single) {
	trd1x = utr1x.f; trd2x = utr2x.f;
	trd1y = utr1y.f; trd2y = utr2y.f;
	trd1z = utr1z.f; trd2z = utr2z.f;
	} else {
	trd1x = utr1x.d; trd2x = utr2x.d;
	trd1y = utr1y.d; trd2y = utr2y.d;
	trd1z = utr1z.d; trd2z = utr2z.d;
	}

	dfix = 2.0( ski)trd1x * (vd / anorm4);
	dfjx = 2.0(-sjk)trd2x * (vd / anorm4);
	dfkx = -(dfix + dfjx);

	dfiy = 2.0( ski)trd1y * (vd / anorm4);
	dfjy = 2.0(-sjk)trd2y * (vd / anorm4);
	dfky = -(dfiy + dfjy);

	dfiz = 2.0( ski)trd1z * (vd / anorm4);
	dfjz = 2.0(-sjk)trd2z * (vd / anorm4);
	dfkz = -(dfiz + dfjz);
	}

	if(triplet_debug) /* Compare forces to numerical derivatives */
	force_debug_3v(xx,i,j,k, k,i,j,
	dfix,dfiy,dfiz,
	dfjx,dfjy,dfjz,
	dfkx,dfky,dfkz);

	if(three_body_forces)
	accumulate_forces_3(w3);

	}

	if(T31 != 0) {
	//printf("T31 i,j,k = %d,%d,%d\n",i,j,k);
	mcount++;
	if(three_body_energies && evflag) {
	tr3 = transtrace(T31->H1H2,T31->H1H2);
	double dvir = (2.0(dvir_ki + dvir_ij)splinepot.vd +
	splinepot.dvd)tr3w3/anorm4;
	vir3v = vir3v + dvir;
	xvir3v = xvir3v + dvir;
	}

	{
	const double vd = splinepot.vd;

	tr_trace3(&(T31->H1H2.m[1][0]),
	&(T31->H1xH2.m[1][0]),&utr1x.d,
	&(T31->H1yH2.m[1][0]),&utr1y.d,
	&(T31->H1zH2.m[1][0]),&utr1z.d);
	tr_trace3(&(T31->H1H2.m[1][0]),
	&(T31->H1H2x.m[1][0]),&utr2x.d,
	&(T31->H1H2y.m[1][0]),&utr2y.d,
	&(T31->H1H2z.m[1][0]),&utr2z.d);
	if(linalg.single) {
	trd1x = utr1x.f; trd2x = utr2x.f;
	trd1y = utr1y.f; trd2y = utr2y.f;
	trd1z = utr1z.f; trd2z = utr2z.f;
	} else {
	trd1x = utr1x.d; trd2x = utr2x.d;
	trd1y = utr1y.d; trd2y = utr2y.d;
	trd1z = utr1z.d; trd2z = utr2z.d;
	}

	dfjx = 2.0( sij)trd1x * (vd / anorm4);
	dfkx = 2.0(-ski)trd2x * (vd / anorm4);
	dfix = -(dfjx + dfkx);

	dfjy = 2.0( sij)trd1y * (vd / anorm4);
	dfky = 2.0(-ski)trd2y * (vd / anorm4);
	dfiy = -(dfjy + dfky);

	dfjz = 2.0( sij)trd1z * (vd / anorm4);
	dfkz = 2.0(-ski)trd2z * (vd / anorm4);
	dfiz = -(dfjz + dfkz);

	}

	if(triplet_debug) /* Compare forces to numerical derivatives */
	force_debug_3v(xx,i,j,k, i,j,k,
	dfix,dfiy,dfiz,
	dfjx,dfjy,dfjz,
	dfkx,dfky,dfkz);

	if(three_body_forces)
	accumulate_forces_3(w3);
	}

	v33 = tr0 / anorm3;
	v43 = (tr1 + tr2 + tr3) / anorm4;
	double de_triplet = (splinepot.vcv33 + splinepot.vdv43) * e_scale * w3;
	e_triplet = e_triplet + de_triplet;
	e_triplet_c = e_triplet_c + splinepot.vcv33 e_scale * w3;
	c_t++;

	//printf("xxxx %6d %6d %6d :: %20.10e\n",1,2,3,de_triplet);

	if(evflag) {
	double drji[3],drki[3];
	double fj[3] = {fjx,fjy,fjz},fk[3] = {fkx,fky,fkz};
	for(int p = 0; p<3; p++) {
	drji[p] = xx[j][p] - xx[i][p];
	drki[p] = xx[k][p] - xx[i][p];
	/* To fix stress-per-atom scaling. */
	fj[p] *= e_scale;
	fk[p] *= e_scale;
	}

	ev_tally3(i,j,k,de_triplet,0.0,fj,fk,drji,drki);

	if(volpres_flag && vflag_atom) {
	//virial[i] = virial[i] - (vir3v + vir3t) * rhoinv*e_scale;
	double dvir = -(xvir3v + xvir3t) * rhoinve_scale (1.0/3.0);
	for(int pp = 0; pp<3; pp++) {
	vatom[i][pp] += dvir;
	vatom[j][pp] += dvir;
	vatom[k][pp] += dvir;
	}
	}

	fix = fix+fsave[0][0]; fiy = fiy+fsave[0][1]; fiz = fiz+fsave[0][2];
	fjx = fjx+fsave[1][0]; fjy = fjy+fsave[1][1]; fjz = fjz+fsave[1][2];
	fkx = fkx+fsave[2][0]; fky = fky+fsave[2][1]; fkz = fkz+fsave[2][2];
	}

	tx1 = gettime();
	ttriplet += tx1 - tx0;
	nttriplet++;
	} else {
	triplet_defer = 1;
	}

	if(four_body_energies \|\| four_body_forces)
	if(j < i) { /* Search for quadruplet */
	tx0 = gettime();

	mj = first[j];
	mk = first[k];
	/*
	i is in both the j-list and the k-list, and i > k,
	and lists are sorted, so the loop terminates.
	*/
	while(nlist_short[mj] < i && nlist_short[mk] < i) {

	if(mj >= first[j+1] \|\| mk >= first[k+1]) {
	printf("Illegal quad...\n"
	" j=%d first[j]=%d first[j+1]=%d mj=%d\n"
	" k=%d first[k]=%d first[k+1]=%d mk=%d\n",
	j,first[j],first[j+1],mj,
	k,first[k],first[k+1],mk);
	error->one(__FILE__,__LINE__,"Shit, brkoen quad loop");
	}

	if(nlist_short[mj] == nlist_short[mk]) {
	/* Closed quadruplet */
	m = nlist_short[mj];
	c_jm = c_km = 1;

	const int sim = (i < m) ? 1 : -1;
	const int sjm = (j < m) ? 1 : -1;
	const int skm = (k < m) ? 1 : -1;

	w4 = get_weight(triclinic,ss[i],ss[j],ss[k],ss[m]);

	if(w4 > 0.0) {

	/* Alrady know ij,jk,ki,jm,km bonds. Look for im bond. */
	mi = first[i];
	while(mi < first[i+1] && nlist_short[mi] < m) mi = mi + 1;
	if(mi < first[i+1] && nlist_short[mi] == m)
	c_im = 1;
	else
	c_im = 0;

	if(c_im == 0 \|\| c_jk == 0 \|\| (c_jk && c_im && m < k)) {

	if(triplet_defer) {
	dvir_ij = dvir_jk = dvir_ki = 0.0;
	if(c_ij && c_jk)
	T12 = get_triplet(xx,j,i,k,&bond_hash,&T12work,&dvir_ij,&dvir_jk);
	if(c_ki && c_jk)
	T23 = get_triplet(xx,k,i,j,&bond_hash,&T23work,&dvir_ki,&dvir_jk);
	if(c_ij && c_ki)
	T31 = get_triplet(xx,i,j,k,&bond_hash,&T31work,&dvir_ij,&dvir_ki);
	triplet_defer = 0;
	}


	fmx = fmy = fmz = 0.0;
	double xvir4 = 0.0;

	if(evflag) {
	fsave[0][0] = fix; fsave[0][1] = fiy; fsave[0][2] = fiz;
	fsave[1][0] = fjx; fsave[1][1] = fjy; fsave[1][2] = fjz;
	fsave[2][0] = fkx; fsave[2][1] = fky; fsave[2][2] = fkz;
	fsave[3][0] = fmx; fsave[3][1] = fmy; fsave[3][2] = fmz;
	fix = fiy = fiz = 0.0;
	fjx = fjy = fjz = 0.0;
	fkx = fky = fkz = 0.0;
	fmx = fmy = fmz = 0.0;
	}

	tr1 = tr2 = tr3 = 0.0;

	dvir_im = dvir_jm = dvir_km = 0.0;
	T45 = T56 = T64 = 0;
	if(T12 != 0 && c_km && c_im)
	T45 = get_triplet(xx,m,i,k,&bond_hash,&T45work,&dvir_im,&dvir_km);
	if(T23 != 0 && c_im && c_jm)
	T56 = get_triplet(xx,m,i,j,&bond_hash,&T56work,&dvir_im,&dvir_jm);
	if(T31 != 0 && c_jm && c_km)
	T64 = get_triplet(xx,m,j,k,&bond_hash,&T64work,&dvir_jm,&dvir_km);

	if(T12 != 0 && T45 != 0) {
	if(four_body_energies && evflag) {
	tr1 = transtrace(T12->H1H2,T45->H1H2);
	double dvir = ( (dvir_ij + dvir_jk + dvir_im + dvir_km)*splinepot.ve +
	splinepot.dve )tr1w4/anorm4;
	vir4 = vir4 + dvir;
	xvir4 = xvir4 + dvir;
	}
	qcount++;

	{
	const double ve = splinepot.ve;

	trd_update_4(T12,T45);

	dfix_update_4a(x);
	dfix_update_4a(y);
	dfix_update_4a(z);
	}

	if(quad_debug) /* Compare forces to numerical derivatives */
	force_debug_4(xx,i,j,k,m, i,j,k,m,
	dfix,dfiy,dfiz , dfjx,dfjy,dfjz,
	dfkx,dfky,dfkz , dfmx,dfmy,dfmz);

	if(four_body_forces)
	accumulate_forces_4(w4);
	}

	if(T23 != 0 && T56 != 0) {
	if(four_body_energies && evflag) {
	tr2 = transtrace(T23->H1H2,T56->H1H2);
	double dvir = ( (dvir_ki + dvir_jk + dvir_im + dvir_jm)*splinepot.ve +
	splinepot.dve )tr2w4/anorm4;
	vir4 = vir4 + dvir;
	xvir4 = xvir4 + dvir;
	}
	qcount++;

	{
	const double ve = splinepot.ve;

	trd_update_4(T23,T56);

	dfix_update_4b(x);
	dfix_update_4b(y);
	dfix_update_4b(z);
	}

	if(quad_debug) /* Compare forces to numerical derivatives */
	force_debug_4(xx,i,j,k,m, i,m,j,k,
	dfix,dfiy,dfiz , dfjx,dfjy,dfjz,
	dfkx,dfky,dfkz , dfmx,dfmy,dfmz);

	if(four_body_forces)
	accumulate_forces_4(w4);

	}

	if(T31 != 0 && T64 != 0) {
	if(four_body_energies && evflag) {
	tr3 = transtrace(T31->H1H2,T64->H1H2);
	double dvir = ( (dvir_ki + dvir_ij + dvir_jm + dvir_km)*splinepot.ve +
	splinepot.dve )tr3w4/anorm4;
	vir4 = vir4 + dvir;
	xvir4 = xvir4 + dvir;
	}
	qcount++;

	{
	const double ve = splinepot.ve;

	/* X */
	trd_update_4(T31,T64);

	dfix_update_4c(x);
	dfix_update_4c(y);
	dfix_update_4c(z);
	}

	if(quad_debug) /* Compare forces to numerical derivatives */
	force_debug_4(xx,i,j,k,m, i,j,m,k,
	dfix,dfiy,dfiz , dfjx,dfjy,dfjz,
	dfkx,dfky,dfkz , dfmx,dfmy,dfmz);

	if(four_body_forces)
	accumulate_forces_4(w4);
	}

	double de_quad = splinepot.ve(tr1 + tr2 + tr3)/anorm4 e_scale * w4;
	e_quad = e_quad + de_quad;
	if((T12 && T45) \|\|
	(T23 && T56) \|\|
	(T31 && T64)) {
	c_q++;
	}

	if(evflag) {
	double drim[3],drjm[3],drkm[3];
	double fi[3] = {fix,fiy,fiz};
	double fj[3] = {fjx,fjy,fjz};
	double fk[3] = {fkx,fky,fkz};
	for(int p = 0; p<3; p++) {
	drim[p] = xx[i][p] - xx[m][p];
	drjm[p] = xx[j][p] - xx[m][p];
	drkm[p] = xx[k][p] - xx[m][p];
	fi[p] *= e_scale;
	fj[p] *= e_scale;
	fk[p] *= e_scale;
	}

	ev_tally4(i,j,k,m,de_quad,fi,fj,fk,drim,drjm,drkm);

	if(volpres_flag && vflag_atom) {
	//virial[i] = virial[i] - vir4 * rhoinv*e_scale;
	double dvir = -xvir4 * rhoinve_scale (1.0/4.0);
	for(int pp = 0; pp<3; pp++) {
	vatom[i][pp] += dvir;
	vatom[j][pp] += dvir;
	vatom[k][pp] += dvir;
	vatom[m][pp] += dvir;
	}
	}

	fix = fix+fsave[0][0]; fiy = fiy+fsave[0][1]; fiz = fiz+fsave[0][2];
	fjx = fjx+fsave[1][0]; fjy = fjy+fsave[1][1]; fjz = fjz+fsave[1][2];
	fkx = fkx+fsave[2][0]; fky = fky+fsave[2][1]; fkz = fkz+fsave[2][2];
	fmx = fmx+fsave[3][0]; fmy = fmy+fsave[3][1]; fmz = fmz+fsave[3][2];
	}

	ff[m][0] += fmx * e_scale;
	ff[m][1] += fmy * e_scale;
	ff[m][2] += fmz * e_scale;

	}
	}
	mj = mj + 1;
	mk = mk + 1;
	} else if(nlist_short[mj] < nlist_short[mk]) {
	mj = mj + 1;
	} else {
	mk = mk + 1;
	}

	}
	tx1 = gettime();
	tquad += tx1 - tx0;
	ntquad++;
	ntquaditer++;
	}


	ff[k][0] += fkx * e_scale;
	ff[k][1] += fky * e_scale;
	ff[k][2] += fkz * e_scale;

	}
	#undef transtrace

	ff[j][0] += fjx * e_scale;
	ff[j][1] += fjy * e_scale;
	ff[j][2] += fjz * e_scale;

	}

	ff[i][0] += fix * e_scale;
	ff[i][1] += fiy * e_scale;
	ff[i][2] += fiz * e_scale;

	if(single_energies == 1 && i < nloc) {
	const double evol0 = splinepot.evol0;
	if(eflag_global) {
	e_single = e_single + evol0 * e_scale;
	eng_vdwl = eng_vdwl + evol0 * e_scale;
	}
	if(eflag_atom) eatom[i] = eatom[i] + evol0 * e_scale;
	if(volpres_flag && vflag_atom) {
	for(int pp = 0; pp<3; pp++)
	vatom[i][pp] = vatom[i][pp] - rhoinvsplinepot.devol0e_scale;
	}

	}

	}

	tx0 = gettime();
	for(i = 0; i<ntot; i++)
	for(p = 0; p<3; p++)
	atom->f[i][p] = atom->f[i][p] + ff[i][p];

	memory->sfree(nlist_short);
	memory->sfree(first);
	if(ss != xx) memory->sfree(ss);
	memory->sfree(ff);
	memory->sfree(xx);
	tx1 = gettime();
	tmem += tx1-tx0;
	ntmem++;

	t1 = gettime(1);

	//printf("compute_x: c_p = %d c_t = %d c_q = %d\n",c_p,c_t,c_q);


	#ifdef TIMING_ON
	if(comm->me == 0) {
	double tsum = (tmem+tsort+tpair+tlookup+ttriplet+tquad);
	double nsum = (ntmem+ntsort+ntpair+ntlookup+nttriplet+ntquad);
	//double adj = ((t1-t0)-tsum)/nsum;
	/* Use adj = 6ns for RDTSC, and 58ns for gettimeofday,
	on monkfish.llnl.gov, 2.4GHz Intel

	Use adj = 35.945ns for RDTSC on uBGL (assumed rate set to 700MHz)
	*/
	double adj = 35.945e-9;

	double
	memadj = tmem - adj*ntmem ,
	sortadj = tsort - adj*ntsort ,
	pairadj = tpair - adj*ntpair ,
	lookupadj = tlookup - adj*ntlookup ,
	tripletadj = ttriplet - adj*nttriplet,
	quadadj = tquad - adj*ntquad ,

	make_b_adj = t_make_b - adj*n_make,
	make_t_adj = t_make_t - adj*n_make,
	make_b2_adj = t_make_b2 - adj*n_make_b2,
	trace_adj = t_trace - adj*n_trace;

	printf("mgpt engy = %10.3fms\n",(t1-t0)*1e3);
	printf(" mem = %10.3fms n = %8.0f adj = %10.3fms one = %10.3fns\n",
	tmem1e3,ntmem,memadj1e3,memadj/ntmem*1e9);
	printf(" sort = %10.3fms n = %8.0f adj = %10.3fms one = %10.3fns\n",
	tsort1e3,ntsort,sortadj1e3,sortadj/ntsort*1e9);
	printf(" pair = %10.3fms n = %8.0f adj = %10.3fms one = %10.3fns\n",
	tpair1e3,ntpair,pairadj1e3,pairadj/ntpair*1e9);
	printf(" lookup = %10.3fms n = %8.0f adj = %10.3fms one = %10.3fns\n",
	tlookup1e3,ntlookup,lookupadj1e3,lookupadj/ntlookup*1e9);
	printf(" triplet = %10.3fms n = %8.0f adj = %10.3fms one = %10.3fns\n",
	ttriplet1e3,nttriplet,tripletadj1e3,tripletadj/nttriplet*1e9);
	printf(" quad = %10.3fms n = %8.0f adj = %10.3fms one = %10.3fns\n",
	tquad1e3,ntquaditer,quadadj1e3,quadadj/ntquaditer*1e9);
	printf(" sum = %10.3fms adj = %10.3fms\n",
	tsum1e3,(tsum - adjnsum)*1e3);
	printf("\n make_b = %10.3fms n = %8.0f adj = %10.3fms one = %10.3fns\n",
	t_make_b1e3,n_make,make_b_adj1e3,make_b_adj/n_make*1e9);
	printf(" make_b2 = %10.3fms n = %8.0f adj = %10.3fms one = %10.3fns\n",
	t_make_b21e3,n_make_b2,make_b2_adj1e3,make_b2_adj/n_make_b2*1e9);
	printf(" make_t = %10.3fms n = %8.0f adj = %10.3fms one = %10.3fns\n\n",
	t_make_t1e3,n_make,make_t_adj1e3,make_t_adj/n_make*1e9);
	printf(" trace = %10.3fms n = %8.0f adj = %10.3fms one = %10.3fns\n\n",
	t_trace1e3,n_trace,trace_adj1e3,trace_adj/n_trace*1e9);

	printf("mcount (transpose + trace for triplet) = %.0f , %.0f qcount = %.0f lmax = %d\n",
	mcount,mcount2,qcount,lmax);

	printf("nbc=%.0f tbl=%.3fms tbm=%.3fms one tbl=%.3fns one tbm=%.3fns\n",
	nbc,(tbl-adjnbc)1e3,(tbm-adjnbc)1e3,(tbl/nbc-adj)*1e9,
	(tbm/nbc-adj)*1e9);
	printf("\n\nForces:\n");
	printf("fix = %.3f fiy=%.3f fiz=%.3f\n",fix,fiy,fiz);
	printf("fjx = %.3f fjy=%.3f fjz=%.3f\n",fjx,fjy,fjz);
	printf("fkx = %.3f fky=%.3f fkz=%.3f\n",fkx,fky,fkz);
	printf("\n");

	printf("Bonds : nsearch=%d maxlen=%d avg.len=%.3f\n",
	bond_hash.NSearch(),bond_hash.MaxLength(),
	bond_hash.NStep()/(double) bond_hash.NSearch());

	printf("compute_x: c_p = %d c_t = %d c_q = %d\n",c_p,c_t,c_q);

	printf("@@ Total number of trace3 calls is %d, total number of make_triplet is %.1f\n",
	ntr_calls,n_make);

	{
	Hash<bond_data,Doublet>::Iterator iter = bond_hash.begin();
	int nitem = 0,nhit = 0;
	while(iter != bond_hash.end()) {
	nitem++;
	nhit += iter.link()->hits;
	iter.next();
	}
	printf("bond_hash hits: nitems=%d nhits=%d hits/item = %.3f\n",
	nitem,nhit,nhit/(double) nitem);
	}
	}
	#endif

	if(volpres_flag) {
	/*
	Include contributions to the pressure due to derivatines
	of the energy with respect to the potential input volume.
	*/

	/* The following lines have moved to beginning of functions,
	since they are used in calculating per-atom virial contributions */
	/*
	double vtot = 1.0;
	double ntot = atom->natoms;
	for(i = 0; i<3; i++)
	vtot = vtot * (domain->boxhi[i] - domain->boxlo[i]);
	double rhoinv = vtot / ntot;
	*/

	if(single_energies) // Virial correction for self energy
	for(i = 0; i<3; i++) {
	//virial[i] = virial[i] + nlocpot_input_volpvol0*e_scale;
	virial[i] = virial[i] - nlocrhoinvsplinepot.devol0*e_scale;
	}

	if(pair_energies) // Virial correction for pair energy
	for(i = 0; i<3; i++)
	virial[i] = virial[i] + rhoinve_scalevolvir2;

	if(three_body_energies) // Virial correction for three body enegries
	for(i = 0; i<3; i++) {
	//virial[i] = virial[i] - pot_input_vol(e_triplet_cpc + (e_triplet-e_triplet_c)*pd);
	virial[i] = virial[i] - (vir3v + vir3t) * rhoinv*e_scale;
	}

	if(four_body_energies) // Virial correction for four body enegries
	for(i = 0; i<3; i++) {
	//virial[i] = virial[i] - pot_input_vole_quadpe;
	virial[i] = virial[i] - vir4 * rhoinv*e_scale;
	}

	}

	*e_s = e_single;
	*e_p = e_pair;
	*e_t = e_triplet;
	*e_q = e_quad;
	}

	void PairMGPT::compute(int eflag, int vflag)
	{
	if(eflag \|\| vflag) ev_setup(eflag, vflag);
	else evflag = vflag_fdotr = eflag_global = vflag_global = eflag_atom = vflag_atom = 0;

	int newton_pair = force->newton_pair;
	double e_s,e_p,e_t,e_q;

	//printf("newton_pair = %d, newton = %d, tag_enable = %d\n",force->newton_pair,force->newton,atom->tag_enable);

	if(newton_pair == 0) {
	printf("This is a problem. MGPT requires newton_pair flag to be on. Exiting...\n");
	exit(1);
	}

	if(atom->tag_enable == 0) {
	printf("This is a problem. MGPT requires tag_enable flag to be on. Exiting...\n");
	exit(1);
	}

	compute_x(listfull->numneigh,listfull->firstneigh,&e_s,&e_p,&e_t,&e_q,evflag,newton_pair);

	if(0) { // Stupid force calculation / verification
	int ii,nmax=-1;
	for(ii = 0; ii<listfull->inum + listfull->gnum; ii++) {
	int i = listfull->ilist[ii];
	if(i > nmax) nmax = i;
	}
	nmax++;
	double ffwork = new double[3nmax];
	double ffloc = new double[3listfull->inum];
	double ffloc2 = new double[3listfull->inum];
	double *ffptr = new double [nmax];
	for(ii = 0; ii<listfull->inum + listfull->gnum; ii++)
	ffptr[ii] = &ffwork[3*ii];

	printf("Computing boundary forces\n");
	for(ii = 0; ii<listfull->inum; ii++) {
	ffloc2[3*ii] = 0.0;
	ffloc2[3*ii+1] = 0.0;
	ffloc2[3*ii+2] = 0.0;
	int i = listfull->ilist[ii];
	for(int jj = 0; jj<listfull->inum+listfull->gnum; jj++) {
	int j = listfull->ilist[jj];
	if(atom->tag[i] == atom->tag[j])
	for(int p = 0; p<3; p++)
	ffloc2[3*ii+p] += atom->f[j][p];
	}
	}

	printf("Starting main displacement force calculation\n");
	for(ii = 0; ii<listfull->inum; ii++) {
	int i = listfull->ilist[ii];

	double **atom_f_save = atom->f;
	atom->f = ffptr;

	for(int p = 0; p<3; p++) {
	double xsave = atom->x[i][p];
	const double delta = 1e-3;

	atom->x[i][p] = xsave + delta;
	for(int jj = 0; jj<3*nmax; jj++) ffwork[jj] = 0.0;
	compute_x(listfull->numneigh,
	listfull->firstneigh,
	&e_s,&e_p,&e_t,&e_q,evflag,newton_pair);
	double e1 = e_s + e_p + e_t + e_q;

	atom->x[i][p] = xsave - delta;
	for(int jj = 0; jj<3*nmax; jj++) ffwork[jj] = 0.0;
	compute_x(listfull->numneigh,
	listfull->firstneigh,
	&e_s,&e_p,&e_t,&e_q,evflag,newton_pair);
	double e2 = e_s + e_p + e_t + e_q;

	ffloc[3ii+p] = -(e1-e2)/(2delta);

	atom->x[i][p] = xsave;
	}

	atom->f = atom_f_save;
	printf("Force on i=%4d:\n",i);
	printf(" Position %20.10e %20.10e %20.10e\n",
	atom->x[i][0],atom->x[i][1],atom->x[i][2]);
	printf(" Exact %20.10e %20.10e %20.10e\n",
	atom->f[i][0],atom->f[i][1],atom->f[i][2]);
	printf(" Numerical %20.10e %20.10e %20.10e\n",
	ffloc[3ii+0],ffloc[3ii+1],ffloc[3*ii+2]);
	printf(" Boundary %20.10e %20.10e %20.10e\n",
	ffloc2[3ii+0],ffloc2[3ii+1],ffloc2[3*ii+2]);
	}


	delete[] ffloc2;
	delete[] ffloc;
	delete[] ffptr;
	delete[] ffwork;
	}


	if(0) {
	printf("\nForces MGPT:\n");
	const int iimax = (listfull->inum < 10) ? listfull->inum : 10;
	for(int ii = 0; ii<iimax; ii++) {
	int i = listfull->ilist[ii];
	printf("%4d = %20.10e %20.10e %20.10e\n",
	i,atom->f[i][0],atom->f[i][1],atom->f[i][2]);
	}
	printf("\n\n");
	}

	if(vflag_fdotr) {
	//printf("##### Using virial_compute!!!\n");
	virial_fdotr_compute();
	}
	}

	void PairMGPT::allocate()
	{
	allocated = 1;
	int n = atom->ntypes;

	memory->create(setflag,n+1,n+1,"pair:setflag");
	for(int i = 0; i <= n; i++)
	for(int j = 0; j <= n; j++)
	setflag[i][j] = 0;

	memory->create(cutsq,n+1,n+1,"pair:cutsq");
	memory->create(cutghost,n+1,n+1,"pair:cutsq");
	}

	/* ----------------------------------------------------------------------
	global settings
	------------------------------------------------------------------------- */
	void PairMGPT::settings(int narg, char **arg)
	{
	if(narg != 0) error->all(__FILE__,__LINE__,"Illegal pair_style command");
	}

	/* ----------------------------------------------------------------------
	set coeffs for one or more type pairs
	------------------------------------------------------------------------- */

	void PairMGPT::coeff(int narg, char **arg)
	{
	int single_precision = 0;

	if(narg < 5)
	error->all(__FILE__,__LINE__,
	"Not enough arguments for mgpt (MGPT) pair coefficients.");

	if(!allocated) allocate();

	// Make sure I,J args are * *
	if(strcmp(arg[0],"") != 0 \|\| strcmp(arg[1],"") != 0)
	error->all(__FILE__,__LINE__,"Incorrect args for pair coefficients");

	double vol;
	if(sscanf(arg[4], "%lg", &vol) != 1 \|\| vol <= 0.0)
	error->all(__FILE__,__LINE__,"Invalid volume in mgpt (MGPT) pair coefficients.");

	volpres_flag = 1;
	single_precision = 0;

	/* Parse arguments */ {
	int volpres_tag = 0,precision_tag = 0,nbody_tag = 0;

	int iarg = 5;
	while (iarg < narg) {
	if(strcmp(arg[iarg],"volpress") == 0) { /* Volumetric pressure flag */
	if (iarg+2 > narg)
	error->all(FLERR,"Incorrect args for pair coefficients");
	if(strcmp(arg[iarg+1],"yes") == 0) volpres_flag = 1;
	else if(strcmp(arg[iarg+1],"no") == 0) volpres_flag = 0;
	else {
	char line[1024];
	sprintf(line,"(In %s:%d) Invalid value for volumetric pressure argument.\n"
	"It should be \"volpress yes\" or \"volpress no\".\n"
	"The value is \"%s\".\n",__FILE__,__LINE__,arg[iarg+1]);
	error->all(__FILE__,__LINE__,line);
	}
	volpres_tag = 1;
	iarg += 2;
	if(comm->me == 0) printf("* volpress: volpres_flag = %d [%s %s]\n",volpres_flag,arg[iarg-2],arg[iarg-1]);
	} else if(strcmp(arg[iarg],"nbody") == 0) {
	if (iarg+2 > narg)
	error->all(FLERR,"Incorrect args for pair coefficients");
	if(strspn(arg[iarg+1],"1234") == strlen(arg[iarg+1])) {
	nbody_flag = 0;
	for(int i = 0; i<4; i++)
	if(strchr(arg[iarg+1],'1'+i) != NULL) {
	nbody_flag = nbody_flag + (1<<i);
	if(comm->me == 0) printf("Explicitly adding %d-tuple forces.\n",i+1);
	}
	} else {
	char line[1024];
	sprintf(line,"(In %s:%d) Invalid value for nbody flag.\n"
	"It should be e.g. \"nbody=1234\" (for single, pair, triple, and quad forces/energiers)\n"
	"For e.g. only pair and triple forces/energies, use \"nbody=23\".\n"
	"The default is \"nbody=1234\".\n"
	"The current value is \"%s\".\n",__FILE__,__LINE__,arg[iarg+1]);
	error->all(__FILE__,__LINE__,line);
	}
	nbody_tag = 1;
	iarg += 2;
	} else if(strcmp(arg[iarg],"precision") == 0) {
	if (iarg+2 > narg)
	error->all(FLERR,"Incorrect args for pair coefficients");
	if(strcmp(arg[iarg+1],"single") == 0) single_precision = 1;
	else if(strcmp(arg[iarg+1],"double") == 0) single_precision = 0;
	else {
	char line[1024];
	sprintf(line,"(In %s:%d) Invalid value for precision argument.\n"
	"It should be \"precision single\" or \"precision double\".\n"
	"The value is \"%s\".\n",__FILE__,__LINE__,arg[iarg+1]);
	error->all(__FILE__,__LINE__,line);
	}
	precision_tag = 1;
	iarg += 2;
	if(comm->me == 0) printf("* precision: single_flag = %d [%s %s]\n",single_precision,arg[iarg-2],arg[iarg-1]);
	} else {
	char line[1024];
	sprintf(line,"(In %s:%d) Invalid argument. Allowed arguments are:\n"
	" volpress {yes\|no} , default = yes\n"
	" precision {single\|double} , default = double\n"
	" nbody {[1234,]*} , default = whichever terms potential require\n"
	"The invalid argument is \"%s\".\n",__FILE__,__LINE__,arg[iarg]);
	error->all(__FILE__,__LINE__,line);
	}
	}

	if(comm->me == 0)
	printf("Volumetric pressure is %s.\n",volpres_flag ? "on" : "off");

	if(comm->me == 0) {
	FILE *parmin_fp = force->open_potential(arg[2]);
	FILE *potin_fp = force->open_potential(arg[3]);
	if (parmin_fp == NULL \|\| potin_fp == NULL) {
	char str[128];
	sprintf(str,"Cannot open MGPT potential files %s %s",arg[2],arg[3]);
	error->one(FLERR,str);
	}
	fclose(parmin_fp);
	fclose(potin_fp);

	splinepot.readpot(arg[2],arg[3],vol);
	printf("evol0 = %.10e\n",splinepot.evol0);

	/* Set up default and requested nbody forces to include */ {
	int nbody_default = (1<<0) + (1<<1) + (1<<2) + (1<<3);

	if(splinepot.vd == 0.0 && splinepot.dvd == 0.0)
	nbody_default -= (1<<2); // No 3-body contributions
	if(splinepot.ve == 0.0 && splinepot.dve == 0.0)
	nbody_default -= (1<<3); // No 4-body contributions

	if(nbody_tag == 0) nbody_flag = nbody_default;

	if(nbody_flag != nbody_default) {
	printf("Warning: nbody=%d (suggested=%d) set to disregard multibody-forces in potential.\n",
	nbody_flag,nbody_default);
	}
	}
	}
	}

	MPI_Bcast(&nbody_flag,sizeof(nbody_flag),MPI_BYTE,0,world);

	/*
	Broadcast structure to all processes. In receiving
	processes, pointes will be screwed up. We allocate
	memory, and then broadcast contents of arrays.
	*/
	MPI_Bcast(&splinepot,sizeof(splinepot),MPI_BYTE,0,world);
	if(comm->me != 0) {
	splinepot.vpair_spline = new double[splinepot.nr-1][4];
	splinepot.dvpair_spline = new double[splinepot.nr-1][4];
	}
	MPI_Bcast(splinepot.vpair_spline,4*(splinepot.nr-1),MPI_DOUBLE,0,world);
	MPI_Bcast(splinepot.dvpair_spline,4*(splinepot.nr-1),MPI_DOUBLE,0,world);
	anorm3 = splinepot.anorm3;
	anorm4 = splinepot.anorm4;
	lmax = splinepot.lmax;
	lang = splinepot.lang;
	//ipot = splinepot.ipot;
	for(int i = 0; i<(int) (sizeof(ddl)/sizeof(double)); i++)
	ddl[i] = splinepot.ddl[i];
	for(int i = 0; i<lmax; i++) {
	for(int j = 0; j<lmax; j++)
	del0.m[i+1][j+1] = 0.0;
	del0.m[i+1][i+1] = 1.0;
	}

	/* Set matrix param, cutoff, LAMMPS param */
	Matrix::sz = lmax;

	rcrit = splinepot.rcrit;
	rmax = splinepot.rmax;
	cutoff = rmax;
	if(rcrit > rmax) cutoff = rcrit;

	// Set LAMMPS pair interaction flags.
	for(int i = 1; i <= atom->ntypes; i++) {
	for(int j = 1; j <= atom->ntypes; j++) {
	setflag[i][j] = 1;
	cutsq[i][j] = cutoff;
	cutghost[i][j] = cutoff;
	}
	}

	// Set atomic mass.
	for(int i = 1; i <= atom->ntypes; i++)
	atom->set_mass(FLERR,i, splinepot.mass);

	// Initialize linear algebra routines.
	linalg = mgpt_linalg(lmax,single_precision);
	if(comm->me == 0)
	printf("%s",linalg.msg);
	}


	/* ----------------------------------------------------------------------
	init specific to this pair style
	------------------------------------------------------------------------- */
	void PairMGPT::init_style()
	{
	if(force->newton_pair == 0)
	error->all(__FILE__,__LINE__,"Pair style mgpt requires newton pair on.");

	// Need full neighbor list.
	int irequest_full = neighbor->request(this);
	neighbor->requests[irequest_full]->id = 1;
	neighbor->requests[irequest_full]->half = 0;
	neighbor->requests[irequest_full]->full = 1;
	neighbor->requests[irequest_full]->ghost = 1;

	// Also need half neighbor list.
	int irequest_half = neighbor->request(this);
	neighbor->requests[irequest_half]->id = 2;
	neighbor->requests[irequest_half]->half = 0;
	neighbor->requests[irequest_half]->half_from_full = 1;
	neighbor->requests[irequest_half]->otherlist = irequest_full;

	}

	/* ----------------------------------------------------------------------
	neighbor callback to inform pair style of neighbor list to use
	half or full
	------------------------------------------------------------------------- */
	void PairMGPT::init_list(int id, NeighList *ptr)
	{
	if(id == 1) listfull = ptr;
	else if(id == 2) listhalf = ptr;
	}

	/* ----------------------------------------------------------------------
	init for one type pair i,j and corresponding j,i
	------------------------------------------------------------------------- */
	double PairMGPT::init_one(int i, int j)
	{
	return cutoff;
	}

	/************************************************************************
	** REIMPLEMENTATION OF FL AND HAMLTN WITH ANALYTICAL DERIVATIVES **
	************************************************************************/
	/*
	Reimplementation of bond length potential, including
	derivatives with respect to x,y, and z.
	*/
	void PairMGPT::fl_deriv_new(double r,double ri,double xhat,double yhat,double zhat,
	double &fl_0,double &fl_x,double &fl_y,double &fl_z,
	double &fl_rp,double &fl_p1,double &fl_r0,double &fl_al) {
	const double rp = splinepot.rp,p1 = splinepot.p1,r0 = splinepot.r00,al = splinepot.al;
	const int mode = splinepot.mode;
	const double pn = splinepot.pn;

	double t,tx,ty,tz,t_rp_ti,t_p1_ti;
	double s;

	/*
	// Original code
	double term;
	double pn=1.0;
	if (mode <= 4)
	term = pow(rp/r, p1);
	else
	term = exp(-p1*(pow(r/rp, pn) - 1.0)/pn);
	*/

	double rpi = 1.0/rp;
	if(mode <= 4) {
	t = pow(rp*ri,p1);
	s = -p1 * t * ri;
	t_rp_ti = p1*rpi;
	t_p1_ti = log(rp*ri);
	} else {
	if(pn == 1.0) {
	double p1_rpi = -p1*rpi;
	t = exp(p1 + r*p1_rpi);
	s = p1_rpi * t;
	t_rp_ti = -rp1_rpirpi;
	t_p1_ti = 1.0 - r*rpi;
	} else {
	double pni = 1.0/pn;
	double rprpn = pow(r*rpi,pn);
	t = exp(-p1pni(rprpn - 1.0));
	s = -p1rprpnri * t;
	t_rp_ti = p1rprpnrpi;
	t_p1_ti = pni - pnirprpn;// -pni(rprpn - 1.0);
	}
	}
	tx = s * xhat;
	ty = s * yhat;
	tz = s * zhat;

	fl_rp = t_rp_ti;
	fl_p1 = t_p1_ti;

	if (r <= r0) {
	fl_0 = t;
	fl_x = tx;
	fl_y = ty;
	fl_z = tz;

	fl_r0 = 0.0;
	fl_al = 0.0;
	} else {
	double q,qx,qy,qz,exp_q,q_r0,q_al;
	double r0i,u;

	r0i = 1.0/r0;
	u = r*r0i - 1.0;
	q = aluu;
	s = 2alu*r0i;
	qx = s * xhat;
	qy = s * yhat;
	qz = s * zhat;
	q_r0 = -2.0alurr0i*r0i;
	q_al = u*u;

	exp_q = exp(-q);
	if(mode <= 2) {
	fl_0 = exp_q * t;
	fl_x = exp_q(tx - tqx);
	fl_y = exp_q(ty - tqy);
	fl_z = exp_q(tz - tqz);

	fl_r0 = -q_r0;
	fl_al = -q_al;
	} else {
	fl_0 = exp_q * (1.0 + q) * t;
	fl_x = exp_q * (tx + q(tx - tqx));
	fl_y = exp_q * (ty + q(ty - tqy));
	fl_z = exp_q * (tz + q(tz - tqz));

	fl_r0 = -q_r0 * q/(1.0 + q);
	fl_al = -q_al * q/(1.0 + q);
	}
	}
	}


	/*
	Macros to build elements of the bond matrix, and also
	its derivatives with repsect to x,y, and z.
	*/
	#define MAKE_ELEMENT_5(i,j) \
	do { \
	const double dl0 = del0.m[i][j]; \
	const double dl4 = gsl_##i * gsl_##j; \
	const double dl4x = gsl_##i##x * gsl_##j + gsl_##i * gsl_##j##x; \
	const double dl4y = gsl_##i##y * gsl_##j + gsl_##i * gsl_##j##y; \
	const double dl4z = gsl_##i##z * gsl_##j + gsl_##i * gsl_##j##z; \
	\
	const double tmp = w4dl4 + w2dl2 + w0*dl0; \
	const double tmpx = w4dl4x + w2dl2x; \
	const double tmpy = w4dl4y + w2dl2y; \
	const double tmpz = w4dl4z + w2dl2z; \
	const double tmpsum = tmpxx + tmpyy + tmpz*z; \
	M [j][i] = M[i][j] = fl *tmp; \
	Mx[j][i] = Mx[i][j] = fl_xtmp + fl_ri(tmpx - x*tmpsum); \
	My[j][i] = My[i][j] = fl_ytmp + fl_ri(tmpy - y*tmpsum); \
	Mz[j][i] = Mz[i][j] = fl_ztmp + fl_ri(tmpz - z*tmpsum); \
	} while(0)

	#define MAKE_ELEMENT_7(i,j) \
	do { \
	const double dl0 = del0.m[i][j]; \
	const double dl6 = gsl_##i * gsl_##j; \
	const double dl6x = gsl_##i##x * gsl_##j + gsl_##i * gsl_##j##x; \
	const double dl6y = gsl_##i##y * gsl_##j + gsl_##i * gsl_##j##y; \
	const double dl6z = gsl_##i##z * gsl_##j + gsl_##i * gsl_##j##z; \
	\
	const double tmp = w6dl6 + w4dl4 + w2dl2 + w0dl0; \
	const double tmpx = w6dl6x + w4dl4x + w2*dl2x; \
	const double tmpy = w6dl6y + w4dl4y + w2*dl2y; \
	const double tmpz = w6dl6z + w4dl4z + w2*dl2z; \
	const double tmpsum = tmpxx + tmpyy + tmpz*z; \
	M [j][i] = M[i][j] = fl *tmp; \
	Mx[j][i] = Mx[i][j] = fl_xtmp + fl_ri(tmpx - x*tmpsum); \
	My[j][i] = My[i][j] = fl_ytmp + fl_ri(tmpy - y*tmpsum); \
	Mz[j][i] = Mz[i][j] = fl_ztmp + fl_ri(tmpz - z*tmpsum); \
	} while(0)
	/* End of bond matrix macros */


	/*
	Construction of bond matrix, and its derivatives
	with respect to the coordinates
	*/
	void PairMGPT::hamltn_5_raw(const double xin,const double yin,const double zin,
	double M [8][8],double Mx[8][8],
	double My[8][8],double Mz[8][8],
	double *fl_deriv_sum_p) {

	const double r = sqrt(xinxin + yinyin + zin*zin),ri = 1.0/r;
	const double x = xinri,y = yinri,z = zin*ri;

	// d-d
	// call delndd(x,y,z)
	const double x2 = xx,y2 = yy,z2 = z*z;
	const double xy = xy,xz = xz,yz = y*z;

	const double sr3 = sqrt(3.0),sr3i = 1.0/sr3;
	const double frac_1_3 = 1.0/3.0,frac_2_3 = 2.0/3.0,frac_4_3 = 4.0/3.0;

	const double ddl_1 = ddl[1],ddl_2 = ddl[2],ddl_3 = ddl[3];
	const double w4 = ddl_1 - frac_4_3ddl_2 + frac_1_3ddl_3;
	const double w2 = ddl_2 - ddl_3;
	const double w0 = ddl_2;


	//del4
	double gsl_1 ,gsl_2 ,gsl_3 ,gsl_4 ,gsl_5;
	double gsl_1x,gsl_2x,gsl_3x,gsl_4x,gsl_5x;
	double gsl_1y,gsl_2y,gsl_3y,gsl_4y,gsl_5y;
	double gsl_1z,gsl_2z,gsl_3z,gsl_4z,gsl_5z;

	double dl2,dl2x,dl2y,dl2z;

	double fl,fl_x,fl_y,fl_z,fl_ri;
	double fl_rp,fl_p1,fl_r0,fl_al;

	gsl_1 = 0.5(3.0z2 - 1.0);
	gsl_1x = 0.0;
	gsl_1y = 0.0;
	gsl_1z = 3.0*z;

	gsl_2 = sr3*xz;
	gsl_2x = sr3*z;
	gsl_2y = 0.0;
	gsl_2z = sr3*x;

	gsl_3 = sr3*yz;
	gsl_3x = 0.0;
	gsl_3y = sr3*z;
	gsl_3z = sr3*y;

	gsl_4 = sr3(x2 - y2)0.5;
	gsl_4x = sr3*x;
	gsl_4y = -sr3*y;
	gsl_4z = 0.0;

	gsl_5 = sr3*xy;
	gsl_5x = sr3*y;
	gsl_5y = sr3*x;
	gsl_5z = 0.0;

	// Compute bond length potential
	fl_deriv_new(r,ri,x,y,z,fl,fl_x,fl_y,fl_z , fl_rp,fl_p1,fl_r0,fl_al);
	fl_ri = fl*ri;

	*fl_deriv_sum_p =
	fl_rpsplinepot.drp + fl_p1splinepot.dp1 +
	fl_r0splinepot.dr00 + fl_alsplinepot.dal;

	// del2

	//del2.m[1][1] = z2 - 2.0/3.0;
	dl2 = z2 - frac_2_3;
	dl2x = 0.0;
	dl2y = 0.0;
	dl2z = 2*z;
	MAKE_ELEMENT_5(1,1);

	//del2.m[1][2] = xz/sr3;
	dl2 = xz*sr3i;
	dl2x = z*sr3i;
	dl2y = 0.0;
	dl2z = x*sr3i;
	MAKE_ELEMENT_5(1,2);

	//del2.m[1][3] = yz/sr3;
	dl2 = yz*sr3i;
	dl2x = 0.0;
	dl2y = z*sr3i;
	dl2z = y*sr3i;
	MAKE_ELEMENT_5(1,3);

	//del2.m[1][4] = -(x2 - y2)*sr3i;
	dl2 = -(x2 - y2)*sr3i;
	dl2x = -2.0sr3ix;
	dl2y = 2.0sr3iy;
	dl2z = 0.0;
	MAKE_ELEMENT_5(1,4);

	//del2.m[1][5] = -2.0xysr3i;
	dl2 = -2.0xysr3i;
	dl2x = -2.0ysr3i;
	dl2y = -2.0xsr3i;
	dl2z = 0.0;
	MAKE_ELEMENT_5(1,5);

	//del2.m[2][2] = -y2;
	dl2 = -y2;
	dl2x = 0.0;
	dl2y = -2.0*y;
	dl2z = 0.0;
	MAKE_ELEMENT_5(2,2);

	//del2.m[2][3] = xy;
	dl2 = xy;
	dl2x = y;
	dl2y = x;
	dl2z = 0.0;
	MAKE_ELEMENT_5(2,3);

	//del2.m[2][4] = xz;
	dl2 = xz;
	dl2x = z;
	dl2y = 0.0;
	dl2z = x;
	MAKE_ELEMENT_5(2,4);

	//del2.m[2][5] = yz;
	dl2 = yz;
	dl2x = 0.0;
	dl2y = z;
	dl2z = y;
	MAKE_ELEMENT_5(2,5);

	//del2.m[3][3] = -x2;
	dl2 = -x2;
	dl2x = -2.0*x;
	dl2y = 0.0;
	dl2z = 0.0;
	MAKE_ELEMENT_5(3,3);

	//del2.m[3][4] = -yz;
	dl2 = -yz;
	dl2x = 0.0;
	dl2y = -z;
	dl2z = -y;
	MAKE_ELEMENT_5(3,4);

	//del2.m[3][5] = xz;
	dl2 = xz;
	dl2x = z;
	dl2y = 0.0;
	dl2z = x;
	MAKE_ELEMENT_5(3,5);

	//del2.m[4][4] = -z2;
	dl2 = -z2;
	dl2x = 0.0;
	dl2y = 0.0;
	dl2z = -2.0*z;
	MAKE_ELEMENT_5(4,4);

	//del2.m[4][5] = 0.0;
	dl2 = 0.0;
	dl2x = 0.0;
	dl2y = 0.0;
	dl2z = 0.0;
	MAKE_ELEMENT_5(4,5);

	//del2.m[5][5] = -z2;
	dl2 = -z2;
	dl2x = 0.0;
	dl2y = 0.0;
	dl2z = -2.0*z;
	MAKE_ELEMENT_5(5,5);
	}


	void PairMGPT::hamltn_7_raw(const double xin,const double yin,const double zin,
	double M [8][8],double Mx[8][8],
	double My[8][8],double Mz[8][8],
	double *fl_deriv_sum_p) {

	const double r = sqrt(xinxin + yinyin + zin*zin),ri = 1.0/r;
	const double x = xinri,y = yinri,z = zin*ri;

	// d-d
	// call delndd(x,y,z)
	const double x2 = xx,y2 = yy,z2 = z*z;
	const double xy = xy,xz = xz,yz = y*z;
	const double x4 = x2x2,y4 = y2y2;

	//const double sr3 = sqrt(3.0);//,sr3i = 1.0/sr3;
	//const double frac_1_3 = 1.0/3.0,frac_2_3 = 2.0/3.0,frac_4_3 = 4.0/3.0;

	const double sr01 = sqrt(0.1);
	const double sr015 = sqrt(0.15);
	const double sr024 = sqrt(0.24);
	const double sr0375 = sqrt(0.375);
	const double sr06 = sqrt(0.6);
	const double sr0625 = sqrt(0.625);
	const double sr09 = sqrt(0.9);
	const double sr15 = sqrt(1.5);
	const double sr24 = sqrt(2.4);
	const double sr36 = sqrt(3.6);
	const double sr375 = sqrt(3.75);
	const double sr96 = sqrt(9.6);
	const double sr150 = sqrt(15.0);



	const double ddl_1 = ddl[1],ddl_2 = ddl[2],ddl_3 = ddl[3],ddl_4 = ddl[4];
	const double w6 = ddl_1 - 1.5ddl_2 + 0.6ddl_3 - 0.1*ddl_4;
	const double w4 = 0.625ddl_2 - ddl_3 + 0.375ddl_4;
	const double w2 = 0.625*(ddl_2 - ddl_4);
	const double w0 = 0.625ddl_2 + 0.375ddl_4;


	//del6
	double gsl_1 ,gsl_2 ,gsl_3 ,gsl_4 ,gsl_5 ,gsl_6, gsl_7;
	double gsl_1x,gsl_2x,gsl_3x,gsl_4x,gsl_5x,gsl_6x,gsl_7x;
	double gsl_1y,gsl_2y,gsl_3y,gsl_4y,gsl_5y,gsl_6y,gsl_7y;
	double gsl_1z,gsl_2z,gsl_3z,gsl_4z,gsl_5z,gsl_6z,gsl_7z;

	double dl2,dl2x,dl2y,dl2z;
	double dl4,dl4x,dl4y,dl4z;
	double t1;

	double fl,fl_x,fl_y,fl_z,fl_ri;
	double fl_rp,fl_p1,fl_r0,fl_al;

	//gslf[1] = 0.5(5.0n2 - 3.0)*n;
	gsl_1 = 0.5(5.0z2 - 3.0)*z;
	gsl_1x = 0.0;
	gsl_1y = 0.0;
	gsl_1z = 7.5*z2 - 1.5;

	//gslf[2] = sr0375(5.0n2 - 1.0)*l;
	gsl_2 = sr0375(5.0z2 - 1.0)*x;
	gsl_2x = sr0375(5.0z2 - 1.0);
	gsl_2y = 0.0;
	gsl_2z = sr037510.0xz;

	//gslf[3] = sr0375(5.0n2 - 1.0)*m;
	gsl_3 = sr0375(5.0z2 - 1.0)*y;
	gsl_3x = 0.0;
	gsl_3y = sr0375(5.0z2 - 1.0);
	gsl_3z = sr037510.0yz;

	//gslf[4] = sr375(l2 - m2)n;
	gsl_4 = sr375(x2 - y2)z;
	gsl_4x = 2.0sr375xz;
	gsl_4y = -2.0sr375yz;
	gsl_4z = sr375*(x2 - y2);

	//gslf[5] = sr150lmn;
	gsl_5 = sr150xyz;
	gsl_5x = sr150*yz;
	gsl_5y = sr150*xz;
	gsl_5z = sr150*xy;

	//gslf[6] = sr0625(l2 - 3.0m2)*l;
	gsl_6 = sr0625(x2 - 3.0y2)*x;
	gsl_6x = 3.0sr0625(x2 - y2);
	gsl_6y = -6.0sr0625xy;
	gsl_6z = 0.0;

	//gslf[7] = sr0625(3.0l2 - m2)*m;
	gsl_7 = sr0625(3.0x2 - y2)*y;
	gsl_7x = 6.0sr0625xy;
	gsl_7y = 3.0sr0625(x2 - y2);
	gsl_7z = 0.0;


	// Compute bond length potential
	fl_deriv_new(r,ri,x,y,z,fl,fl_x,fl_y,fl_z , fl_rp,fl_p1,fl_r0,fl_al);
	fl_ri = fl*ri;

	*fl_deriv_sum_p =
	fl_rpsplinepot.drp + fl_p1splinepot.dp1 +
	fl_r0splinepot.dr00 + fl_alsplinepot.dal;

	// del2f

	//del2f.m[1][1] = 0.4(3.0n2 - 1.0);
	dl2 = 0.4(3.0z2 - 1.0);
	dl2x = 0.0;
	dl2y = 0.0;
	dl2z = 2.4*z;

	//del4f.m[1][1] = 0.60(5.0n2 - 4.0)*n2;
	dl4 = 0.60(5.0z2 - 4.0)*z2;
	dl4x = 0.0;
	dl4y = 0.0;
	dl4z = 0.60(20.0z2 - 8.0)*z;

	MAKE_ELEMENT_7(1,1);


	//del2f.m[1][2] = sr024*ln;
	dl2 = sr024*xz;
	dl2x = sr024*z;
	dl2y = 0.0;
	dl2z = sr024*x;

	//del4f.m[1][2] = sr024(5.0n2 - 2.0)*ln;
	dl4 = sr024(5.0z2 - 2.0)*xz;
	dl4x = sr024(5.0z2 - 2.0)*z;
	dl4y = 0.0;
	dl4z = sr024(15.0z2 - 2.0)*x;

	MAKE_ELEMENT_7(1,2);


	//del2f.m[1][3] = sr024*mn;
	dl2 = sr024*yz;
	dl2x = 0.0;
	dl2y = sr024*z;
	dl2z = sr024*y;

	//del4f.m[1][3] = sr024(5.0n2 - 2.0)*mn;
	dl4 = sr024(5.0z2 - 2.0)*yz;
	dl4x = 0.0;
	dl4y = sr024(5.0z2 - 2.0)*z;
	dl4z = sr024(15.0z2 - 2.0)*y;

	MAKE_ELEMENT_7(1,3);


	//del2f.m[1][4] = -sr06*(l2 - m2);
	dl2 = -sr06*(x2 - y2);
	dl2x = -2.0sr06x;
	dl2y = 2.0sr06y;
	dl2z = 0.0;

	//del4f.m[1][4] = -sr06(l2 - m2)n2;
	dl4 = -sr06(x2 - y2)z2;
	dl4x = -2.0sr06x*z2;
	dl4y = 2.0sr06y*z2;
	dl4z = -2.0sr06(x2 - y2)*z;

	MAKE_ELEMENT_7(1,4);


	//del2f.m[1][5] = -sr24*lm;
	dl2 = -sr24*xy;
	dl2x = -sr24*y;
	dl2y = -sr24*x;
	dl2z = 0.0;

	//del4f.m[1][5] = -sr24lmn2;
	dl4 = -sr24xyz2;
	dl4x = -sr24yz2;
	dl4y = -sr24xz2;
	dl4z = -2.0sr24xy*z;

	MAKE_ELEMENT_7(1,5);


	//del2f.m[1][6] = 0.0;
	dl2 = 0.0;
	dl2x = 0.0;
	dl2y = 0.0;
	dl2z = 0.0;

	//del4f.m[1][6] = sr36(3.0m2 - l2)*ln;
	dl4 = sr36(3.0y2 - x2)*xz;
	dl4x = 3.0sr36(y2 - x2)*z;
	dl4y = 6.0sr36y*xz;
	dl4z = sr36(3.0y2 - x2)*x;

	MAKE_ELEMENT_7(1,6);


	//del2f.m[1][7] = 0.0;
	dl2 = 0.0;
	dl2x = 0.0;
	dl2y = 0.0;
	dl2z = 0.0;

	//del4f.m[1][7] = -sr36(3.0l2 - m2)*mn;
	dl4 = -sr36(3.0x2 - y2)*yz;
	dl4x = -6.0sr36x*yz;
	dl4y = -3.0sr36(x2 - y2)*z;
	dl4z = -sr36(3.0x2 - y2)*y;

	MAKE_ELEMENT_7(1,7);


	//del2f.m[2][2] = 0.3(1.0 - 4.0m2 + n2);
	dl2 = 0.3 - 1.2y2 + 0.3z2;
	dl2x = 0.0;
	dl2y = -2.4*y;
	dl2z = 0.6*z;

	//del4f.m[2][2] = -0.4ll - 2.5(m2 - 0.6l2)*n2;
	dl4 = -0.4x2 - 2.5(y2 - 0.6x2)z2;
	dl4x = -0.8x + 3.0x*z2;
	dl4y = -5.0yz2;
	dl4z = -5.0(y2 - 0.6x2)*z;

	MAKE_ELEMENT_7(2,2);


	//del2f.m[2][3] = 1.2*lm;
	dl2 = 1.2*xy;
	dl2x = 1.2*y;
	dl2y = 1.2*x;
	dl2z = 0.0;

	//del4f.m[2][3] = 0.4(10.0n2 - 1.0)*lm;
	dl4 = (4.0z2 - 0.4)xy;
	dl4x = (4.0z2 - 0.4)y;
	dl4y = (4.0z2 - 0.4)x;
	dl4z = 8.0zxy;

	MAKE_ELEMENT_7(2,3);


	//del2f.m[2][4] = sr09*ln;
	dl2 = sr09*xz;
	dl2x = sr09*z;
	dl2y = 0.0;
	dl2z = sr09*x;

	//del4f.m[2][4] = sr01(6.0n2 - 8.0m2 - 1.0)ln;
	dl4 = sr01(6.0z2 - 8.0y2 - 1.0)xz;
	dl4x = sr01(6.0z2 - 8.0y2 - 1.0)z;
	dl4y = -16.0sr01y*xz;
	dl4z = sr01(18.0z2 - 8.0y2 - 1.0)x;

	MAKE_ELEMENT_7(2,4);


	//del2f.m[2][5] = sr09*mn;
	dl2 = sr09*yz;
	dl2x = 0.0;
	dl2y = sr09*z;
	dl2z = sr09*y;

	//del4f.m[2][5] = sr01(2.0n2 - 8.0m2 + 3.0)mn;
	dl4 = sr01(2.0z2 - 8.0y2 + 3.0)yz;
	dl4x = 0.0;
	dl4y = sr01(2.0z2 - 24.0y2 + 3.0)z;
	dl4z = sr01(6.0z2 - 8.0y2 + 3.0)y;

	MAKE_ELEMENT_7(2,5);


	//del2f.m[2][6] = -sr015*(l2 - m2);
	dl2 = -sr015*(x2 - y2);
	dl2x = -2.0sr015x;
	dl2y = 2.0sr015y;
	dl2z = 0.0;

	//del4f.m[2][6] = sr375(l2 - m2 - 1.4l4 + 1.2l2m2 + m4);
	dl4 = sr375(x2 - y2 - 1.4x4 + 1.2x2y2 + y4);
	dl4x = sr375(2.0 - 5.6x2 + 2.4y2)x;
	dl4y = sr375(-2.0 + 2.4x2 + 4.0y2)y;
	dl4z = 0.0;

	MAKE_ELEMENT_7(2,6);


	//del2f.m[2][7] = -sr06*lm;
	dl2 = -sr06*xy;
	dl2x = -sr06*y;
	dl2y = -sr06*x;
	dl2z = 0.0;

	//del4f.m[2][7] = sr96(n2 - l2 + 0.25)lm;
	dl4 = sr96(z2 - x2 + 0.25)xy;
	dl4x = sr96(z2 - 3.0x2 + 0.25)*y;
	dl4y = sr96(z2 - x2 + 0.25)x;
	dl4z = 2.0sr96z*xy;

	MAKE_ELEMENT_7(2,7);


	//del2f.m[3][3] = 0.30(1.0 - 4.0l2 + n2);
	dl2 = 0.3 - 1.2x2 + 0.3z2;
	dl2x = -2.4*x;
	dl2y = 0.0;
	dl2z = 0.6*z;

	//del4f.m[3][3] = -0.4m2 - 2.5(l2 - 0.6m2)n2;
	dl4 = -0.4y2 - 2.5(x2 - 0.6y2)z2;
	dl4x = -5.0xz2;
	dl4y = y(3.0z2 - 0.8);
	dl4z = -5.0(x2 - 0.6y2)*z;

	MAKE_ELEMENT_7(3,3);


	//del2f.m[3][4] = -sr09*mn;
	dl2 = -sr09*yz;
	dl2x = 0.0;
	dl2y = -sr09*z;
	dl2z = -sr09*y;

	//del4f.m[3][4] = -sr01(6.0n2 - 8.0l2 - 1.0)mn;
	dl4 = -sr01(6.0z2 - 8.0x2 - 1.0)yz;
	dl4x = 16.0sr01x*yz;
	dl4y = -sr01(6.0z2 - 8.0x2 - 1.0)z;
	dl4z = -sr01(18.0z2 - 8.0x2 - 1.0)y;

	MAKE_ELEMENT_7(3,4);


	//del2f.m[3][5] = sr09*ln;
	dl2 = sr09*xz;
	dl2x = sr09*z;
	dl2y = 0.0;
	dl2z = sr09*x;

	//del4f.m[3][5] = sr01(2.0n2 - 8.0l2 + 3.0)ln;
	dl4 = sr01(2.0z2 - 8.0x2 + 3.0)xz;
	dl4x = sr01(2.0z2 - 24.0x2 + 3.0)z;
	dl4y = 0.0;
	dl4z = sr01(6.0z2 - 8.0x2 + 3.0)x;

	MAKE_ELEMENT_7(3,5);


	//del2f.m[3][6] = sr06*lm;
	dl2 = sr06*xy;
	dl2x = sr06*y;
	dl2y = sr06*x;
	dl2z = 0.0;

	//del4f.m[3][6] = sr96(m2 - n2 - 0.25)lm;
	dl4 = sr96(y2 - z2 - 0.25)xy;
	dl4x = sr96(y2 - z2 - 0.25)y;
	dl4y = sr96(3.0y2 - z2 - 0.25)*x;
	dl4z = -2.0sr96z*xy;

	MAKE_ELEMENT_7(3,6);


	//del2f.m[3][7] = -sr015*(l2 - m2);
	dl2 = -sr015*(x2 - y2);
	dl2x = -2.0sr015x;
	dl2y = 2.0sr015y;
	dl2z = 0.0;

	//del4f.m[3][7] = sr375(l2 - m2 + 1.4m4 - 1.2l2m2 - l4);
	dl4 = sr375(x2 - y2 + 1.4y4 - 1.2x2y2 - x4);
	dl4x = sr375(2.0 - 2.4y2 - 4.0x2)x;
	dl4y = sr375(-2.0 + 5.6y2 - 2.4x2)y;
	dl4z = 0.0;

	MAKE_ELEMENT_7(3,7);


	//del2f.m[4][4] = 0.0;
	dl2 = 0.0;
	dl2x = 0.0;
	dl2y = 0.0;
	dl2z = 0.0;

	//del4f.m[4][4] = (2.0 - 3.0n2)n2 - 4.0l2m2;
	dl4 = (2.0 - 3.0z2)z2 - 4.0x2y2;
	dl4x = -8.0xy2;
	dl4y = -8.0x2y;
	dl4z = (4.0 - 12.0z2)z;

	MAKE_ELEMENT_7(4,4);

	//del2f.m[4][5] = 0.0;
	dl2 = 0.0;
	dl2x = 0.0;
	dl2y = 0.0;
	dl2z = 0.0;

	//del4f.m[4][5] = 2.0(l2 - m2)lm;
	dl4 = 2.0(x2 - y2)xy;
	dl4x = 2.0(3.0x2 - y2)*y;
	dl4y = 2.0(x2 - 3.0y2)*x;
	dl4z = 0.0;

	MAKE_ELEMENT_7(4,5);


	//del2f.m[4][6] = sr15*ln;
	dl2 = sr15*xz;
	dl2x = sr15*z;
	dl2y = 0.0;
	dl2z = sr15*x;

	//del4f.m[4][6] = -sr15(2.0n2 - 1.0)*ln;
	dl4 = -sr15(2.0z2 - 1.0)*xz;
	dl4x = -sr15(2.0z2 - 1.0)*z;
	dl4y = 0.0;
	dl4z = -sr15(6.0z2 - 1.0)*x;

	MAKE_ELEMENT_7(4,6);


	//del2f.m[4][7] = sr15*mn;
	dl2 = sr15*yz;
	dl2x = 0.0;
	dl2y = sr15*z;
	dl2z = sr15*y;

	//del4f.m[4][7] = -sr15(2.0n2 - 1.0)*mn;
	dl4 = -sr15(2.0z2 - 1.0)*yz;
	dl4x = 0.0;
	dl4y = -sr15(2.0z2 - 1.0)*z;
	dl4z = -sr15(6.0z2 - 1.0)*y;

	MAKE_ELEMENT_7(4,7);


	//del2f.m[5][5] = 0.0;
	dl2 = 0.0;
	dl2x = 0.0;
	dl2y = 0.0;
	dl2z = 0.0;

	//del4f.m[5][5] = -pow((2.0n2 - 1.0),2) + 4.0l2*m2;
	t1 = 2.0*z2 - 1.0;
	dl4 = -t1t1 + 4.0x2*y2;
	dl4x = 8.0xy2;
	dl4y = 8.0x2y;
	dl4z = -8.0t1z;

	MAKE_ELEMENT_7(5,5);


	//del2f.m[5][6] = -sr15*mn;
	dl2 = -sr15*yz;
	dl2x = 0.0;
	dl2y = -sr15*z;
	dl2z = -sr15*y;

	//del4f.m[5][6] = sr15(2.0n2 - 1.0)*mn;
	dl4 = sr15(2.0z2 - 1.0)*yz;
	dl4x = 0.0;
	dl4y = sr15(2.0z2 - 1.0)*z;
	dl4z = sr15(6.0z2 - 1.0)*y;

	MAKE_ELEMENT_7(5,6);

	//del2f.m[5][7] = sr15*ln;
	dl2 = sr15*xz;
	dl2x = sr15*z;
	dl2y = 0.0;
	dl2z = sr15*x;

	//del4f.m[5][7] = -sr15(2.0n2 - 1.0)*ln;
	dl4 = -sr15(2.0z2 - 1.0)*xz;
	dl4x = -sr15(2.0z2 - 1.0)*z;
	dl4y = 0.0;
	dl4z = -sr15(6.0z2 - 1.0)*x;

	MAKE_ELEMENT_7(5,7);


	//del2f.m[6][6] = -(3.0*n2 - 1.0)/2.0;
	dl2 = 0.5 - 1.5*z2;
	dl2x = 0.0;
	dl2y = 0.0;
	dl2z = -3.0*z;

	//del4f.m[6][6] = 1.5(n2 - 1.0)n2;
	dl4 = (1.5z2 - 1.5)z2;
	dl4x = 0.0;
	dl4y = 0.0;
	dl4z = (6.0z2 - 3.0)z;

	MAKE_ELEMENT_7(6,6);


	//del2f.m[6][7] = 0.0;
	dl2 = 0.0;
	dl2x = 0.0;
	dl2y = 0.0;
	dl2z = 0.0;

	//del4f.m[6][7] = 0.0;
	dl4 = 0.0;
	dl4x = 0.0;
	dl4y = 0.0;
	dl4z = 0.0;

	MAKE_ELEMENT_7(6,7);


	//del2f.m[7][7] = -(3.0*n2 - 1.0)/2.0;
	dl2 = 0.5 - 1.5*z2;
	dl2x = 0.0;
	dl2y = 0.0;
	dl2z = -3.0*z;

	//del4f.m[7][7] = 1.5(n2 - 1.0)n2;
	dl4 = (1.5z2 - 1.5)z2;
	dl4x = 0.0;
	dl4y = 0.0;
	dl4z = (6.0z2 - 3.0)z;

	MAKE_ELEMENT_7(7,7);
	}

	/************************************************************************/

	/* ----------------------------------------------------------------------
	* Fast Model Generalized Pseudopotential Theory (MGPT) interatomic
	* potential routine.
	*
	* Copyright (2015) Lawrence Livermore National Security, LLC.
	* Produced at the Lawrence Livermore National Laboratory.
	* Written by Tomas Oppelstrup (oppelstrup2@llnl.gov) and John Moriarty
	* (moriarty2@llnl.gov)
	* LLNL-CODE-674031 All rights reserved.
	*
	* This program is free software; you can redistribute it and/or modify it
	* under the terms of the GNU General Public License (as published by the
	* Free Software Foundation) version 2, dated June 1991.
	*
	* This program is distributed in the hope that it will be useful, but
	* WITHOUT ANY WARRANTY; without even the IMPLIED WARRANTY OF MERCHANTABILITY
	* or FITNESS FOR A PARTICULAR PURPOSE. See the terms and conditions of the
	* GNU General Public License for more details.
	*
	* LLNL Preamble Notice
	* A. This notice is required to be provided under our contract with the
	* U.S. Department of Energy (DOE). This work was performed under the auspices
	* of the DOE by Lawrence Livermore National Laboratory under Contract No.
	* DE-AC52-07NA27344.
	*
	* B. Neither the United States Government nor Lawrence Livermore National
	* Security, LLC nor any of their employees, makes any warranty, express or
	* implied, or assumes any liability or responsibility for the accuracy,
	* completeness, or usefulness of any information, apparatus, product, or
	* process disclosed, or represents that its use would not infringe
	* privately-owned rights.
	*
	* C. Also, reference herein to any specific commercial products, process,
	* or services by trade name, trademark, manufacturer or otherwise does not
	* necessarily constitute or imply its endorsement, recommendation, or
	* favoring by the United States Government or Lawrence Livermore National
	* Security, LLC. The views and opinions of authors expressed herein do not
	* necessarily state or reflect those of the United States Government or
	* Lawrence Livermore National Security, LLC, and shall not be used for
	* advertising or product endorsement purposes.
	------------------------------------------------------------------------- */

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