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pair_table.cpp
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pair_table.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 author: Paul Crozier (SNL)
------------------------------------------------------------------------- */
#include "mpi.h"
#include "math.h"
#include "stdlib.h"
#include "string.h"
#include "pair_table.h"
#include "atom.h"
#include "force.h"
#include "comm.h"
#include "neigh_list.h"
#include "memory.h"
#include "error.h"
using namespace LAMMPS_NS;
#define MIN(a,b) ((a) < (b) ? (a) : (b))
#define MAX(a,b) ((a) > (b) ? (a) : (b))
#define LOOKUP 0
#define LINEAR 1
#define SPLINE 2
#define BITMAP 3
#define R 1
#define RSQ 2
#define BMP 3
#define MAXLINE 1024
/* ---------------------------------------------------------------------- */
PairTable::PairTable(LAMMPS *lmp) : Pair(lmp)
{
ntables = 0;
tables = NULL;
}
/* ---------------------------------------------------------------------- */
PairTable::~PairTable()
{
for (int m = 0; m < ntables; m++) free_table(&tables[m]);
memory->sfree(tables);
if (allocated) {
memory->destroy_2d_int_array(setflag);
memory->destroy_2d_double_array(cutsq);
memory->destroy_2d_int_array(tabindex);
}
}
/* ---------------------------------------------------------------------- */
void PairTable::compute(int eflag, int vflag)
{
int i,j,ii,jj,inum,jnum,itype,jtype,itable;
double xtmp,ytmp,ztmp,delx,dely,delz,evdwl,fpair;
double rsq,factor_lj,fraction,value,a,b;
int *ilist,*jlist,*numneigh,**firstneigh;
Table *tb;
union_int_float_t rsq_lookup;
evdwl = 0.0;
if (eflag || vflag) ev_setup(eflag,vflag);
else evflag = vflag_fdotr = 0;
double **x = atom->x;
double **f = atom->f;
int *type = atom->type;
int nlocal = atom->nlocal;
int nall = nlocal + atom->nghost;
double *special_lj = force->special_lj;
int newton_pair = force->newton_pair;
inum = list->inum;
ilist = list->ilist;
numneigh = list->numneigh;
firstneigh = list->firstneigh;
// loop over neighbors of my atoms
for (ii = 0; ii < inum; ii++) {
i = ilist[ii];
xtmp = x[i][0];
ytmp = x[i][1];
ztmp = x[i][2];
itype = type[i];
jlist = firstneigh[i];
jnum = numneigh[i];
for (jj = 0; jj < jnum; jj++) {
j = jlist[jj];
if (j < nall) factor_lj = 1.0;
else {
factor_lj = special_lj[j/nall];
j %= nall;
}
delx = xtmp - x[j][0];
dely = ytmp - x[j][1];
delz = ztmp - x[j][2];
rsq = delx*delx + dely*dely + delz*delz;
jtype = type[j];
if (rsq < cutsq[itype][jtype]) {
tb = &tables[tabindex[itype][jtype]];
if (rsq < tb->innersq)
error->one("Pair distance < table inner cutoff");
if (tabstyle == LOOKUP) {
itable = static_cast<int> ((rsq - tb->innersq) * tb->invdelta);
if (itable >= nm1)
error->one("Pair distance > table outer cutoff");
fpair = factor_lj * tb->f[itable];
} else if (tabstyle == LINEAR) {
itable = static_cast<int> ((rsq - tb->innersq) * tb->invdelta);
if (itable >= nm1)
error->one("Pair distance > table outer cutoff");
fraction = (rsq - tb->rsq[itable]) * tb->invdelta;
value = tb->f[itable] + fraction*tb->df[itable];
fpair = factor_lj * value;
} else if (tabstyle == SPLINE) {
itable = static_cast<int> ((rsq - tb->innersq) * tb->invdelta);
if (itable >= nm1)
error->one("Pair distance > table outer cutoff");
b = (rsq - tb->rsq[itable]) * tb->invdelta;
a = 1.0 - b;
value = a * tb->f[itable] + b * tb->f[itable+1] +
((a*a*a-a)*tb->f2[itable] + (b*b*b-b)*tb->f2[itable+1]) *
tb->deltasq6;
fpair = factor_lj * value;
} else {
rsq_lookup.f = rsq;
itable = rsq_lookup.i & tb->nmask;
itable >>= tb->nshiftbits;
fraction = (rsq_lookup.f - tb->rsq[itable]) * tb->drsq[itable];
value = tb->f[itable] + fraction*tb->df[itable];
fpair = factor_lj * value;
}
f[i][0] += delx*fpair;
f[i][1] += dely*fpair;
f[i][2] += delz*fpair;
if (newton_pair || j < nlocal) {
f[j][0] -= delx*fpair;
f[j][1] -= dely*fpair;
f[j][2] -= delz*fpair;
}
if (eflag) {
if (tabstyle == LOOKUP)
evdwl = tb->e[itable];
else if (tabstyle == LINEAR || tabstyle == BITMAP)
evdwl = tb->e[itable] + fraction*tb->de[itable];
else
evdwl = a * tb->e[itable] + b * tb->e[itable+1] +
((a*a*a-a)*tb->e2[itable] + (b*b*b-b)*tb->e2[itable+1]) *
tb->deltasq6;
evdwl *= factor_lj;
}
if (evflag) ev_tally(i,j,nlocal,newton_pair,
evdwl,0.0,fpair,delx,dely,delz);
}
}
}
if (vflag_fdotr) virial_compute();
}
/* ----------------------------------------------------------------------
allocate all arrays
------------------------------------------------------------------------- */
void PairTable::allocate()
{
allocated = 1;
int nt = atom->ntypes;
setflag = memory->create_2d_int_array(nt+1,nt+1,"pair:setflag");
for (int i = 1; i <= nt; i++)
for (int j = i; j <= nt; j++)
setflag[i][j] = 0;
cutsq = memory->create_2d_double_array(nt+1,nt+1,"pair:cutsq");
tabindex = memory->create_2d_int_array(nt+1,nt+1,"pair:tabindex");
}
/* ----------------------------------------------------------------------
global settings
------------------------------------------------------------------------- */
void PairTable::settings(int narg, char **arg)
{
if (narg != 2) error->all("Illegal pair_style command");
// new settings
if (strcmp(arg[0],"lookup") == 0) tabstyle = LOOKUP;
else if (strcmp(arg[0],"linear") == 0) tabstyle = LINEAR;
else if (strcmp(arg[0],"spline") == 0) tabstyle = SPLINE;
else if (strcmp(arg[0],"bitmap") == 0) tabstyle = BITMAP;
else error->all("Unknown table style in pair_style command");
n = force->inumeric(arg[1]);
nm1 = n - 1;
// delete old tables, since cannot just change settings
for (int m = 0; m < ntables; m++) free_table(&tables[m]);
memory->sfree(tables);
if (allocated) {
memory->destroy_2d_int_array(setflag);
memory->destroy_2d_double_array(cutsq);
memory->destroy_2d_int_array(tabindex);
}
allocated = 0;
ntables = 0;
tables = NULL;
}
/* ----------------------------------------------------------------------
set coeffs for one or more type pairs
------------------------------------------------------------------------- */
void PairTable::coeff(int narg, char **arg)
{
if (narg != 4 && narg != 5) error->all("Illegal pair_coeff command");
if (!allocated) allocate();
int ilo,ihi,jlo,jhi;
force->bounds(arg[0],atom->ntypes,ilo,ihi);
force->bounds(arg[1],atom->ntypes,jlo,jhi);
int me;
MPI_Comm_rank(world,&me);
tables = (Table *)
memory->srealloc(tables,(ntables+1)*sizeof(Table),"pair:tables");
Table *tb = &tables[ntables];
null_table(tb);
if (me == 0) read_table(tb,arg[2],arg[3]);
bcast_table(tb);
// set table cutoff
if (narg == 5) tb->cut = force->numeric(arg[4]);
else if (tb->rflag) tb->cut = tb->rhi;
else tb->cut = tb->rfile[tb->ninput-1];
// error check on table parameters
// insure cutoff is within table
// for BITMAP tables, file values can be in non-ascending order
if (tb->ninput <= 1) error->one("Invalid pair table length");
double rlo,rhi;
if (tb->rflag == 0) {
rlo = tb->rfile[0];
rhi = tb->rfile[tb->ninput-1];
} else {
rlo = tb->rlo;
rhi = tb->rhi;
}
if (tb->cut <= rlo || tb->cut > rhi) error->all("Invalid pair table cutoff");
if (rlo <= 0.0) error->all("Invalid pair table cutoff");
// match = 1 if don't need to spline read-in tables
// this is only the case if r values needed by final tables
// exactly match r values read from file
tb->match = 0;
if (tabstyle == LINEAR && tb->ninput == n &&
tb->rflag == RSQ && tb->rhi == tb->cut) tb->match = 1;
if (tabstyle == SPLINE && tb->ninput == n &&
tb->rflag == RSQ && tb->rhi == tb->cut) tb->match = 1;
if (tabstyle == BITMAP && tb->ninput == 1 << n &&
tb->rflag == BMP && tb->rhi == tb->cut) tb->match = 1;
if (tb->rflag == BMP && tb->match == 0)
error->all("Bitmapped table in file does not match requested table");
// spline read-in values and compute r,e,f vectors within table
if (tb->match == 0) spline_table(tb);
compute_table(tb);
// store ptr to table in tabindex
int count = 0;
for (int i = ilo; i <= ihi; i++) {
for (int j = MAX(jlo,i); j <= jhi; j++) {
tabindex[i][j] = ntables;
setflag[i][j] = 1;
count++;
}
}
if (count == 0) error->all("Illegal pair_coeff command");
ntables++;
}
/* ----------------------------------------------------------------------
init for one type pair i,j and corresponding j,i
------------------------------------------------------------------------- */
double PairTable::init_one(int i, int j)
{
if (setflag[i][j] == 0) error->all("All pair coeffs are not set");
tabindex[j][i] = tabindex[i][j];
return tables[tabindex[i][j]].cut;
}
/* ----------------------------------------------------------------------
read a table section from a tabulated potential file
only called by proc 0
this function sets these values in Table:
ninput,rfile,efile,ffile,rflag,rlo,rhi,fpflag,fplo,fphi,ntablebits
------------------------------------------------------------------------- */
void PairTable::read_table(Table *tb, char *file, char *keyword)
{
char line[MAXLINE];
// open file
FILE *fp = fopen(file,"r");
if (fp == NULL) {
char str[128];
sprintf(str,"Cannot open file %s",file);
error->one(str);
}
// loop until section found with matching keyword
while (1) {
if (fgets(line,MAXLINE,fp) == NULL)
error->one("Did not find keyword in table file");
if (strspn(line," \t\n") == strlen(line)) continue; // blank line
if (line[0] == '#') continue; // comment
if (strstr(line,keyword) == line) break; // matching keyword
fgets(line,MAXLINE,fp); // no match, skip section
param_extract(tb,line);
fgets(line,MAXLINE,fp);
for (int i = 0; i < tb->ninput; i++) fgets(line,MAXLINE,fp);
}
// read args on 2nd line of section
// allocate table arrays for file values
fgets(line,MAXLINE,fp);
param_extract(tb,line);
tb->rfile = (double *)
memory->smalloc(tb->ninput*sizeof(double),"pair:rfile");
tb->efile = (double *)
memory->smalloc(tb->ninput*sizeof(double),"pair:efile");
tb->ffile = (double *)
memory->smalloc(tb->ninput*sizeof(double),"pair:ffile");
// setup bitmap parameters for table to read in
tb->ntablebits = 0;
int masklo,maskhi,nmask,nshiftbits;
if (tb->rflag == BMP) {
while (1 << tb->ntablebits < tb->ninput) tb->ntablebits++;
if (1 << tb->ntablebits != tb->ninput)
error->one("Bitmapped table is incorrect length in table file");
init_bitmap(tb->rlo,tb->rhi,tb->ntablebits,masklo,maskhi,nmask,nshiftbits);
}
// read r,e,f table values from file
// if rflag set, compute r
// if rflag not set, use r from file
int itmp;
double rtmp;
union_int_float_t rsq_lookup;
fgets(line,MAXLINE,fp);
for (int i = 0; i < tb->ninput; i++) {
fgets(line,MAXLINE,fp);
sscanf(line,"%d %lg %lg %lg",&itmp,&rtmp,&tb->efile[i],&tb->ffile[i]);
if (tb->rflag == R)
rtmp = tb->rlo + (tb->rhi - tb->rlo)*i/(tb->ninput-1);
else if (tb->rflag == RSQ) {
rtmp = tb->rlo*tb->rlo +
(tb->rhi*tb->rhi - tb->rlo*tb->rlo)*i/(tb->ninput-1);
rtmp = sqrt(rtmp);
} else if (tb->rflag == BMP) {
rsq_lookup.i = i << nshiftbits;
rsq_lookup.i |= masklo;
if (rsq_lookup.f < tb->rlo*tb->rlo) {
rsq_lookup.i = i << nshiftbits;
rsq_lookup.i |= maskhi;
}
rtmp = sqrtf(rsq_lookup.f);
}
tb->rfile[i] = rtmp;
}
// close file
fclose(fp);
}
/* ----------------------------------------------------------------------
broadcast read-in table info from proc 0 to other procs
this function communicates these values in Table:
ninput,rfile,efile,ffile,rflag,rlo,rhi,fpflag,fplo,fphi
------------------------------------------------------------------------- */
void PairTable::bcast_table(Table *tb)
{
MPI_Bcast(&tb->ninput,1,MPI_INT,0,world);
int me;
MPI_Comm_rank(world,&me);
if (me > 0) {
tb->rfile = (double *)
memory->smalloc(tb->ninput*sizeof(double),"pair:rfile");
tb->efile = (double *)
memory->smalloc(tb->ninput*sizeof(double),"pair:efile");
tb->ffile = (double *)
memory->smalloc(tb->ninput*sizeof(double),"pair:ffile");
}
MPI_Bcast(tb->rfile,tb->ninput,MPI_DOUBLE,0,world);
MPI_Bcast(tb->efile,tb->ninput,MPI_DOUBLE,0,world);
MPI_Bcast(tb->ffile,tb->ninput,MPI_DOUBLE,0,world);
MPI_Bcast(&tb->rflag,1,MPI_INT,0,world);
if (tb->rflag) {
MPI_Bcast(&tb->rlo,1,MPI_DOUBLE,0,world);
MPI_Bcast(&tb->rhi,1,MPI_DOUBLE,0,world);
}
MPI_Bcast(&tb->fpflag,1,MPI_INT,0,world);
if (tb->fpflag) {
MPI_Bcast(&tb->fplo,1,MPI_DOUBLE,0,world);
MPI_Bcast(&tb->fphi,1,MPI_DOUBLE,0,world);
}
}
/* ----------------------------------------------------------------------
build spline representation of e,f over entire range of read-in table
this function sets these values in Table: e2file,f2file
------------------------------------------------------------------------- */
void PairTable::spline_table(Table *tb)
{
tb->e2file = (double *)
memory->smalloc(tb->ninput*sizeof(double),"pair:e2file");
tb->f2file = (double *)
memory->smalloc(tb->ninput*sizeof(double),"pair:f2file");
double ep0 = - tb->ffile[0];
double epn = - tb->ffile[tb->ninput-1];
spline(tb->rfile,tb->efile,tb->ninput,ep0,epn,tb->e2file);
if (tb->fpflag == 0) {
tb->fplo = (tb->ffile[1] - tb->ffile[0]) / (tb->rfile[1] - tb->rfile[0]);
tb->fphi = (tb->ffile[tb->ninput-1] - tb->ffile[tb->ninput-2]) /
(tb->rfile[tb->ninput-1] - tb->rfile[tb->ninput-2]);
}
double fp0 = tb->fplo;
double fpn = tb->fphi;
spline(tb->rfile,tb->ffile,tb->ninput,fp0,fpn,tb->f2file);
}
/* ----------------------------------------------------------------------
extract attributes from parameter line in table section
format of line: N value R/RSQ/BITMAP lo hi FP fplo fphi
N is required, other params are optional
------------------------------------------------------------------------- */
void PairTable::param_extract(Table *tb, char *line)
{
tb->ninput = 0;
tb->rflag = 0;
tb->fpflag = 0;
char *word = strtok(line," \t\n\r\f");
while (word) {
if (strcmp(word,"N") == 0) {
word = strtok(NULL," \t\n\r\f");
tb->ninput = atoi(word);
} else if (strcmp(word,"R") == 0 || strcmp(word,"RSQ") == 0 ||
strcmp(word,"BITMAP") == 0) {
if (strcmp(word,"R") == 0) tb->rflag = R;
else if (strcmp(word,"RSQ") == 0) tb->rflag = RSQ;
else if (strcmp(word,"BITMAP") == 0) tb->rflag = BMP;
word = strtok(NULL," \t\n\r\f");
tb->rlo = atof(word);
word = strtok(NULL," \t\n\r\f");
tb->rhi = atof(word);
} else if (strcmp(word,"FP") == 0) {
tb->fpflag = 1;
word = strtok(NULL," \t\n\r\f");
tb->fplo = atof(word);
word = strtok(NULL," \t\n\r\f");
tb->fphi = atof(word);
} else {
printf("WORD: %s\n",word);
error->one("Invalid keyword in pair table parameters");
}
word = strtok(NULL," \t\n\r\f");
}
if (tb->ninput == 0) error->one("Pair table parameters did not set N");
}
/* ----------------------------------------------------------------------
compute r,e,f vectors from splined values
------------------------------------------------------------------------- */
void PairTable::compute_table(Table *tb)
{
// inner = inner table bound
// cut = outer table bound
// delta = table spacing in rsq for N-1 bins
double inner;
if (tb->rflag) inner = tb->rlo;
else inner = tb->rfile[0];
tb->innersq = inner*inner;
tb->delta = (tb->cut*tb->cut - tb->innersq) / nm1;
tb->invdelta = 1.0/tb->delta;
// direct lookup tables
// N-1 evenly spaced bins in rsq from inner to cut
// e,f = value at midpt of bin
// e,f are N-1 in length since store 1 value at bin midpt
// f is converted to f/r when stored in f[i]
// e,f are never a match to read-in values, always computed via spline interp
if (tabstyle == LOOKUP) {
tb->e = (double *) memory->smalloc(nm1*sizeof(double),"pair:e");
tb->f = (double *) memory->smalloc(nm1*sizeof(double),"pair:f");
double r,rsq;
for (int i = 0; i < nm1; i++) {
rsq = tb->innersq + (i+0.5)*tb->delta;
r = sqrt(rsq);
tb->e[i] = splint(tb->rfile,tb->efile,tb->e2file,tb->ninput,r);
tb->f[i] = splint(tb->rfile,tb->ffile,tb->f2file,tb->ninput,r)/r;
}
}
// linear tables
// N-1 evenly spaced bins in rsq from inner to cut
// rsq,e,f = value at lower edge of bin
// de,df values = delta from lower edge to upper edge of bin
// rsq,e,f are N in length so de,df arrays can compute difference
// f is converted to f/r when stored in f[i]
// e,f can match read-in values, else compute via spline interp
if (tabstyle == LINEAR) {
tb->rsq = (double *) memory->smalloc(n*sizeof(double),"pair:rsq");
tb->e = (double *) memory->smalloc(n*sizeof(double),"pair:e");
tb->f = (double *) memory->smalloc(n*sizeof(double),"pair:f");
tb->de = (double *) memory->smalloc(nm1*sizeof(double),"pair:de");
tb->df = (double *) memory->smalloc(nm1*sizeof(double),"pair:df");
double r,rsq;
for (int i = 0; i < n; i++) {
rsq = tb->innersq + i*tb->delta;
r = sqrt(rsq);
tb->rsq[i] = rsq;
if (tb->match) {
tb->e[i] = tb->efile[i];
tb->f[i] = tb->ffile[i]/r;
} else {
tb->e[i] = splint(tb->rfile,tb->efile,tb->e2file,tb->ninput,r);
tb->f[i] = splint(tb->rfile,tb->ffile,tb->f2file,tb->ninput,r)/r;
}
}
for (int i = 0; i < nm1; i++) {
tb->de[i] = tb->e[i+1] - tb->e[i];
tb->df[i] = tb->f[i+1] - tb->f[i];
}
}
// cubic spline tables
// N-1 evenly spaced bins in rsq from inner to cut
// rsq,e,f = value at lower edge of bin
// e2,f2 = spline coefficient for each bin
// rsq,e,f,e2,f2 are N in length so have N-1 spline bins
// f is converted to f/r after e is splined
// e,f can match read-in values, else compute via spline interp
if (tabstyle == SPLINE) {
tb->rsq = (double *) memory->smalloc(n*sizeof(double),"pair:rsq");
tb->e = (double *) memory->smalloc(n*sizeof(double),"pair:e");
tb->f = (double *) memory->smalloc(n*sizeof(double),"pair:f");
tb->e2 = (double *) memory->smalloc(n*sizeof(double),"pair:e2");
tb->f2 = (double *) memory->smalloc(n*sizeof(double),"pair:f2");
tb->deltasq6 = tb->delta*tb->delta / 6.0;
double r,rsq;
for (int i = 0; i < n; i++) {
rsq = tb->innersq + i*tb->delta;
r = sqrt(rsq);
tb->rsq[i] = rsq;
if (tb->match) {
tb->e[i] = tb->efile[i];
tb->f[i] = tb->ffile[i]/r;
} else {
tb->e[i] = splint(tb->rfile,tb->efile,tb->e2file,tb->ninput,r);
tb->f[i] = splint(tb->rfile,tb->ffile,tb->f2file,tb->ninput,r);
}
}
// ep0,epn = dE/dr at inner and at cut
double ep0 = - tb->f[0];
double epn = - tb->f[nm1];
spline(tb->rsq,tb->e,n,ep0,epn,tb->e2);
// fp0,fpn = dh/dg at inner and at cut
// h(r) = f(r)/r and g(r) = r^2
// dh/dg = (1/r df/dr - f/r^2) / 2r
// dh/dg in secant approx = (f(r2)/r2 - f(r1)/r1) / (g(r2) - g(r1))
double fp0,fpn;
double secant_factor = 0.1;
if (tb->fpflag) fp0 = (tb->fplo/sqrt(tb->innersq) - tb->f[0]/tb->innersq) /
(2.0 * sqrt(tb->innersq));
else {
double rsq1 = tb->innersq;
double rsq2 = rsq1 + secant_factor*tb->delta;
fp0 = (splint(tb->rfile,tb->ffile,tb->f2file,tb->ninput,sqrt(rsq2)) /
sqrt(rsq2) - tb->f[0] / sqrt(rsq1)) / (secant_factor*tb->delta);
}
if (tb->fpflag && tb->cut == tb->rfile[tb->ninput-1]) fpn =
(tb->fphi/tb->cut - tb->f[nm1]/(tb->cut*tb->cut)) / (2.0 * tb->cut);
else {
double rsq2 = tb->cut * tb->cut;
double rsq1 = rsq2 - secant_factor*tb->delta;
fpn = (tb->f[nm1] / sqrt(rsq2) -
splint(tb->rfile,tb->ffile,tb->f2file,tb->ninput,sqrt(rsq1)) /
sqrt(rsq1)) / (secant_factor*tb->delta);
}
for (int i = 0; i < n; i++) tb->f[i] /= sqrt(tb->rsq[i]);
spline(tb->rsq,tb->f,n,fp0,fpn,tb->f2);
}
// bitmapped linear tables
// 2^N bins from inner to cut, spaced in bitmapped manner
// f is converted to f/r when stored in f[i]
// e,f can match read-in values, else compute via spline interp
if (tabstyle == BITMAP) {
double r;
union_int_float_t rsq_lookup;
int masklo,maskhi;
// linear lookup tables of length ntable = 2^n
// stored value = value at lower edge of bin
init_bitmap(inner,tb->cut,n,masklo,maskhi,tb->nmask,tb->nshiftbits);
int ntable = 1 << n;
int ntablem1 = ntable - 1;
tb->rsq = (double *) memory->smalloc(ntable*sizeof(double),"pair:rsq");
tb->e = (double *) memory->smalloc(ntable*sizeof(double),"pair:e");
tb->f = (double *) memory->smalloc(ntable*sizeof(double),"pair:f");
tb->de = (double *) memory->smalloc(ntable*sizeof(double),"pair:de");
tb->df = (double *) memory->smalloc(ntable*sizeof(double),"pair:df");
tb->drsq = (double *) memory->smalloc(ntable*sizeof(double),"pair:drsq");
union_int_float_t minrsq_lookup;
minrsq_lookup.i = 0 << tb->nshiftbits;
minrsq_lookup.i |= maskhi;
for (int i = 0; i < ntable; i++) {
rsq_lookup.i = i << tb->nshiftbits;
rsq_lookup.i |= masklo;
if (rsq_lookup.f < tb->innersq) {
rsq_lookup.i = i << tb->nshiftbits;
rsq_lookup.i |= maskhi;
}
r = sqrtf(rsq_lookup.f);
tb->rsq[i] = rsq_lookup.f;
if (tb->match) {
tb->e[i] = tb->efile[i];
tb->f[i] = tb->ffile[i]/r;
} else {
tb->e[i] = splint(tb->rfile,tb->efile,tb->e2file,tb->ninput,r);
tb->f[i] = splint(tb->rfile,tb->ffile,tb->f2file,tb->ninput,r)/r;
}
minrsq_lookup.f = MIN(minrsq_lookup.f,rsq_lookup.f);
}
tb->innersq = minrsq_lookup.f;
for (int i = 0; i < ntablem1; i++) {
tb->de[i] = tb->e[i+1] - tb->e[i];
tb->df[i] = tb->f[i+1] - tb->f[i];
tb->drsq[i] = 1.0/(tb->rsq[i+1] - tb->rsq[i]);
}
// get the delta values for the last table entries
// tables are connected periodically between 0 and ntablem1
tb->de[ntablem1] = tb->e[0] - tb->e[ntablem1];
tb->df[ntablem1] = tb->f[0] - tb->f[ntablem1];
tb->drsq[ntablem1] = 1.0/(tb->rsq[0] - tb->rsq[ntablem1]);
// get the correct delta values at itablemax
// smallest r is in bin itablemin
// largest r is in bin itablemax, which is itablemin-1,
// or ntablem1 if itablemin=0
// deltas at itablemax only needed if corresponding rsq < cut*cut
// if so, compute deltas between rsq and cut*cut
// if tb->match, data at cut*cut is unavailable, so we'll take
// deltas at itablemax-1 as a good approximation
double e_tmp,f_tmp;
int itablemin = minrsq_lookup.i & tb->nmask;
itablemin >>= tb->nshiftbits;
int itablemax = itablemin - 1;
if (itablemin == 0) itablemax = ntablem1;
int itablemaxm1 = itablemax - 1;
if (itablemax == 0) itablemaxm1 = ntablem1;
rsq_lookup.i = itablemax << tb->nshiftbits;
rsq_lookup.i |= maskhi;
if (rsq_lookup.f < tb->cut*tb->cut) {
if (tb->match) {
tb->de[itablemax] = tb->de[itablemaxm1];
tb->df[itablemax] = tb->df[itablemaxm1];
tb->drsq[itablemax] = tb->drsq[itablemaxm1];
} else {
rsq_lookup.f = tb->cut*tb->cut;
r = sqrtf(rsq_lookup.f);
e_tmp = splint(tb->rfile,tb->efile,tb->e2file,tb->ninput,r);
f_tmp = splint(tb->rfile,tb->ffile,tb->f2file,tb->ninput,r)/r;
tb->de[itablemax] = e_tmp - tb->e[itablemax];
tb->df[itablemax] = f_tmp - tb->f[itablemax];
tb->drsq[itablemax] = 1.0/(rsq_lookup.f - tb->rsq[itablemax]);
}
}
}
}
/* ----------------------------------------------------------------------
set all ptrs in a table to NULL, so can be freed safely
------------------------------------------------------------------------- */
void PairTable::null_table(Table *tb)
{
tb->rfile = tb->efile = tb->ffile = NULL;
tb->e2file = tb->f2file = NULL;
tb->rsq = tb->drsq = tb->e = tb->de = NULL;
tb->f = tb->df = tb->e2 = tb->f2 = NULL;
}
/* ----------------------------------------------------------------------
free all arrays in a table
------------------------------------------------------------------------- */
void PairTable::free_table(Table *tb)
{
memory->sfree(tb->rfile);
memory->sfree(tb->efile);
memory->sfree(tb->ffile);
memory->sfree(tb->e2file);
memory->sfree(tb->f2file);
memory->sfree(tb->rsq);
memory->sfree(tb->drsq);
memory->sfree(tb->e);
memory->sfree(tb->de);
memory->sfree(tb->f);
memory->sfree(tb->df);
memory->sfree(tb->e2);
memory->sfree(tb->f2);
}
/* ----------------------------------------------------------------------
spline and splint routines modified from Numerical Recipes
------------------------------------------------------------------------- */
void PairTable::spline(double *x, double *y, int n,
double yp1, double ypn, double *y2)
{
int i,k;
double p,qn,sig,un;
double *u = new double[n];
if (yp1 > 0.99e30) y2[0] = u[0] = 0.0;
else {
y2[0] = -0.5;
u[0] = (3.0/(x[1]-x[0])) * ((y[1]-y[0]) / (x[1]-x[0]) - yp1);
}
for (i = 1; i < n-1; i++) {
sig = (x[i]-x[i-1]) / (x[i+1]-x[i-1]);
p = sig*y2[i-1] + 2.0;
y2[i] = (sig-1.0) / p;
u[i] = (y[i+1]-y[i]) / (x[i+1]-x[i]) - (y[i]-y[i-1]) / (x[i]-x[i-1]);
u[i] = (6.0*u[i] / (x[i+1]-x[i-1]) - sig*u[i-1]) / p;
}
if (ypn > 0.99e30) qn = un = 0.0;
else {
qn = 0.5;
un = (3.0/(x[n-1]-x[n-2])) * (ypn - (y[n-1]-y[n-2]) / (x[n-1]-x[n-2]));
}
y2[n-1] = (un-qn*u[n-2]) / (qn*y2[n-2] + 1.0);
for (k = n-2; k >= 0; k--) y2[k] = y2[k]*y2[k+1] + u[k];
delete [] u;
}
/* ---------------------------------------------------------------------- */
double PairTable::splint(double *xa, double *ya, double *y2a, int n, double x)
{
int klo,khi,k;
double h,b,a,y;
klo = 0;
khi = n-1;
while (khi-klo > 1) {
k = (khi+klo) >> 1;
if (xa[k] > x) khi = k;
else klo = k;
}
h = xa[khi]-xa[klo];
a = (xa[khi]-x) / h;
b = (x-xa[klo]) / h;
y = a*ya[klo] + b*ya[khi] +
((a*a*a-a)*y2a[klo] + (b*b*b-b)*y2a[khi]) * (h*h)/6.0;
return y;
}
/* ----------------------------------------------------------------------
proc 0 writes to restart file
------------------------------------------------------------------------- */
void PairTable::write_restart(FILE *fp)
{
write_restart_settings(fp);
}
/* ----------------------------------------------------------------------
proc 0 reads from restart file, bcasts
------------------------------------------------------------------------- */
void PairTable::read_restart(FILE *fp)
{
read_restart_settings(fp);
allocate();
}
/* ----------------------------------------------------------------------
proc 0 writes to restart file
------------------------------------------------------------------------- */
void PairTable::write_restart_settings(FILE *fp)
{
fwrite(&tabstyle,sizeof(int),1,fp);
fwrite(&n,sizeof(int),1,fp);
}
/* ----------------------------------------------------------------------
proc 0 reads from restart file, bcasts
------------------------------------------------------------------------- */
void PairTable::read_restart_settings(FILE *fp)
{
if (comm->me == 0) {
fread(&tabstyle,sizeof(int),1,fp);
fread(&n,sizeof(int),1,fp);
}
MPI_Bcast(&tabstyle,1,MPI_DOUBLE,0,world);
MPI_Bcast(&n,1,MPI_INT,0,world);
nm1 = n - 1;
}
/* ---------------------------------------------------------------------- */
double PairTable::single(int i, int j, int itype, int jtype, double rsq,
double factor_coul, double factor_lj,
double &fforce)
{
int itable;
double fraction,value,a,b,phi;
Table *tb = &tables[tabindex[itype][jtype]];
if (rsq < tb->innersq) error->one("Pair distance < table inner cutoff");
if (tabstyle == LOOKUP) {
itable = static_cast<int> ((rsq-tb->innersq) * tb->invdelta);
if (itable >= nm1) error->one("Pair distance > table outer cutoff");
fforce = factor_lj * tb->f[itable];
} else if (tabstyle == LINEAR) {
itable = static_cast<int> ((rsq-tb->innersq) * tb->invdelta);
if (itable >= nm1) error->one("Pair distance > table outer cutoff");
fraction = (rsq - tb->rsq[itable]) * tb->invdelta;
value = tb->f[itable] + fraction*tb->df[itable];
fforce = factor_lj * value;
} else if (tabstyle == SPLINE) {
itable = static_cast<int> ((rsq-tb->innersq) * tb->invdelta);
if (itable >= nm1) error->one("Pair distance > table outer cutoff");
b = (rsq - tb->rsq[itable]) * tb->invdelta;
a = 1.0 - b;
value = a * tb->f[itable] + b * tb->f[itable+1] +
((a*a*a-a)*tb->f2[itable] + (b*b*b-b)*tb->f2[itable+1]) *
tb->deltasq6;
fforce = factor_lj * value;
} else {
union_int_float_t rsq_lookup;
rsq_lookup.f = rsq;
itable = rsq_lookup.i & tb->nmask;
itable >>= tb->nshiftbits;
fraction = (rsq_lookup.f - tb->rsq[itable]) * tb->drsq[itable];
value = tb->f[itable] + fraction*tb->df[itable];
fforce = factor_lj * value;
}
if (tabstyle == LOOKUP)
phi = tb->e[itable];
else if (tabstyle == LINEAR || tabstyle == BITMAP)
phi = tb->e[itable] + fraction*tb->de[itable];
else
phi = a * tb->e[itable] + b * tb->e[itable+1] +
((a*a*a-a)*tb->e2[itable] + (b*b*b-b)*tb->e2[itable+1]) * tb->deltasq6;
return factor_lj*phi;
}
/* ----------------------------------------------------------------------
return the Coulomb cutoff for tabled potentials
called by KSpace solvers which require that all pairwise cutoffs be the same
loop over all tables not just those indexed by tabindex[i][j] since
no way to know which tables are active since pair::init() not yet called
------------------------------------------------------------------------- */
void *PairTable::extract(char *str)
{
if (strcmp(str,"cut_coul") != 0) return NULL;
if (ntables == 0) error->all("All pair coeffs are not set");
double cut_coul = tables[0].cut;
for (int m = 1; m < ntables; m++)
if (tables[m].cut != cut_coul)
error->all("Pair table cutoffs must all be equal to use with KSpace");
return &tables[0].cut;
}

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