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angle_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: Chuanfu Luo (luochuanfu@gmail.com)
------------------------------------------------------------------------- */
#include <math.h>
#include <stdlib.h>
#include <string.h>
#include "angle_table.h"
#include "atom.h"
#include "neighbor.h"
#include "domain.h"
#include "comm.h"
#include "force.h"
#include "math_const.h"
#include "memory.h"
#include "error.h"
using namespace LAMMPS_NS;
using namespace MathConst;
enum{LINEAR,SPLINE};
#define MAXLINE 1024
#define SMALL 0.001
#define TINY 1.E-10
/* ---------------------------------------------------------------------- */
AngleTable::AngleTable(LAMMPS *lmp) : Angle(lmp)
{
writedata = 0;
ntables = 0;
tables = NULL;
}
/* ---------------------------------------------------------------------- */
AngleTable::~AngleTable()
{
for (int m = 0; m < ntables; m++) free_table(&tables[m]);
memory->sfree(tables);
if (allocated) {
memory->destroy(setflag);
memory->destroy(theta0);
memory->destroy(tabindex);
}
}
/* ---------------------------------------------------------------------- */
void AngleTable::compute(int eflag, int vflag)
{
int i1,i2,i3,n,type;
double eangle,f1[3],f3[3];
double delx1,dely1,delz1,delx2,dely2,delz2;
double rsq1,rsq2,r1,r2,c,s,a,a11,a12,a22;
double theta,u,mdu; //mdu: minus du, -du/dx=f
eangle = 0.0;
if (eflag || vflag) ev_setup(eflag,vflag);
else evflag = 0;
double **x = atom->x;
double **f = atom->f;
int **anglelist = neighbor->anglelist;
int nanglelist = neighbor->nanglelist;
int nlocal = atom->nlocal;
int newton_bond = force->newton_bond;
for (n = 0; n < nanglelist; n++) {
i1 = anglelist[n][0];
i2 = anglelist[n][1];
i3 = anglelist[n][2];
type = anglelist[n][3];
// 1st bond
delx1 = x[i1][0] - x[i2][0];
dely1 = x[i1][1] - x[i2][1];
delz1 = x[i1][2] - x[i2][2];
rsq1 = delx1*delx1 + dely1*dely1 + delz1*delz1;
r1 = sqrt(rsq1);
// 2nd bond
delx2 = x[i3][0] - x[i2][0];
dely2 = x[i3][1] - x[i2][1];
delz2 = x[i3][2] - x[i2][2];
rsq2 = delx2*delx2 + dely2*dely2 + delz2*delz2;
r2 = sqrt(rsq2);
// angle (cos and sin)
c = delx1*delx2 + dely1*dely2 + delz1*delz2;
c /= r1*r2;
if (c > 1.0) c = 1.0;
if (c < -1.0) c = -1.0;
s = sqrt(1.0 - c*c);
if (s < SMALL) s = SMALL;
s = 1.0/s;
// tabulated force & energy
theta = acos(c);
uf_lookup(type,theta,u,mdu);
if (eflag) eangle = u;
a = mdu * s;
a11 = a*c / rsq1;
a12 = -a / (r1*r2);
a22 = a*c / rsq2;
f1[0] = a11*delx1 + a12*delx2;
f1[1] = a11*dely1 + a12*dely2;
f1[2] = a11*delz1 + a12*delz2;
f3[0] = a22*delx2 + a12*delx1;
f3[1] = a22*dely2 + a12*dely1;
f3[2] = a22*delz2 + a12*delz1;
// apply force to each of 3 atoms
if (newton_bond || i1 < nlocal) {
f[i1][0] += f1[0];
f[i1][1] += f1[1];
f[i1][2] += f1[2];
}
if (newton_bond || i2 < nlocal) {
f[i2][0] -= f1[0] + f3[0];
f[i2][1] -= f1[1] + f3[1];
f[i2][2] -= f1[2] + f3[2];
}
if (newton_bond || i3 < nlocal) {
f[i3][0] += f3[0];
f[i3][1] += f3[1];
f[i3][2] += f3[2];
}
if (evflag) ev_tally(i1,i2,i3,nlocal,newton_bond,eangle,f1,f3,
delx1,dely1,delz1,delx2,dely2,delz2);
}
}
/* ---------------------------------------------------------------------- */
void AngleTable::allocate()
{
allocated = 1;
int n = atom->nangletypes;
memory->create(theta0,n+1,"angle:theta0");
memory->create(tabindex,n+1,"angle:tabindex");
memory->create(setflag,n+1,"angle:setflag");
for (int i = 1; i <= n; i++) setflag[i] = 0;
}
/* ----------------------------------------------------------------------
global settings
------------------------------------------------------------------------- */
void AngleTable::settings(int narg, char **arg)
{
if (narg != 2) error->all(FLERR,"Illegal angle_style command");
if (strcmp(arg[0],"linear") == 0) tabstyle = LINEAR;
else if (strcmp(arg[0],"spline") == 0) tabstyle = SPLINE;
else error->all(FLERR,"Unknown table style in angle style table");
tablength = force->inumeric(FLERR,arg[1]);
if (tablength < 2) error->all(FLERR,"Illegal number of angle table entries");
// 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(setflag);
memory->destroy(tabindex);
}
allocated = 0;
ntables = 0;
tables = NULL;
}
/* ----------------------------------------------------------------------
set coeffs for one or more type pairs
------------------------------------------------------------------------- */
void AngleTable::coeff(int narg, char **arg)
{
if (narg != 3) error->all(FLERR,"Illegal angle_coeff command");
if (!allocated) allocate();
int ilo,ihi;
force->bounds(arg[0],atom->nangletypes,ilo,ihi);
int me;
MPI_Comm_rank(world,&me);
tables = (Table *)
memory->srealloc(tables,(ntables+1)*sizeof(Table),"angle:tables");
Table *tb = &tables[ntables];
null_table(tb);
if (me == 0) read_table(tb,arg[1],arg[2]);
bcast_table(tb);
// error check on table parameters
if (tb->ninput <= 1) error->one(FLERR,"Invalid angle table length");
double alo,ahi;
alo = tb->afile[0];
ahi = tb->afile[tb->ninput-1];
if (fabs(alo-0.0) > TINY || fabs(ahi-180.0) > TINY)
error->all(FLERR,"Angle table must range from 0 to 180 degrees");
// convert theta from degrees to radians
for (int i = 0; i < tb->ninput; i++){
tb->afile[i] *= MY_PI/180.0;
tb->ffile[i] *= 180.0/MY_PI;
}
// spline read-in and compute a,e,f vectors within table
spline_table(tb);
compute_table(tb);
// store ptr to table in tabindex
int count = 0;
for (int i = ilo; i <= ihi; i++) {
tabindex[i] = ntables;
setflag[i] = 1;
theta0[i] = tb->theta0;
count++;
}
ntables++;
if (count == 0) error->all(FLERR,"Illegal angle_coeff command");
}
/* ----------------------------------------------------------------------
return an equilbrium angle length
should not be used, since don't know minimum of tabulated function
------------------------------------------------------------------------- */
double AngleTable::equilibrium_angle(int i)
{
return theta0[i];
}
/* ----------------------------------------------------------------------
proc 0 writes to restart file
------------------------------------------------------------------------- */
void AngleTable::write_restart(FILE *fp)
{
fwrite(&tabstyle,sizeof(int),1,fp);
fwrite(&tablength,sizeof(int),1,fp);
}
/* ----------------------------------------------------------------------
proc 0 reads from restart file, bcasts
------------------------------------------------------------------------- */
void AngleTable::read_restart(FILE *fp)
{
if (comm->me == 0) {
fread(&tabstyle,sizeof(int),1,fp);
fread(&tablength,sizeof(int),1,fp);
}
MPI_Bcast(&tabstyle,1,MPI_INT,0,world);
MPI_Bcast(&tablength,1,MPI_INT,0,world);
allocate();
}
/* ---------------------------------------------------------------------- */
double AngleTable::single(int type, int i1, int i2, int i3)
{
double **x = atom->x;
double delx1 = x[i1][0] - x[i2][0];
double dely1 = x[i1][1] - x[i2][1];
double delz1 = x[i1][2] - x[i2][2];
domain->minimum_image(delx1,dely1,delz1);
double r1 = sqrt(delx1*delx1 + dely1*dely1 + delz1*delz1);
double delx2 = x[i3][0] - x[i2][0];
double dely2 = x[i3][1] - x[i2][1];
double delz2 = x[i3][2] - x[i2][2];
domain->minimum_image(delx2,dely2,delz2);
double r2 = sqrt(delx2*delx2 + dely2*dely2 + delz2*delz2);
double c = delx1*delx2 + dely1*dely2 + delz1*delz2;
c /= r1*r2;
if (c > 1.0) c = 1.0;
if (c < -1.0) c = -1.0;
double theta = acos(c);
double u=0.0;
u_lookup(type,theta,u);
return u;
}
/* ---------------------------------------------------------------------- */
void AngleTable::null_table(Table *tb)
{
tb->afile = tb->efile = tb->ffile = NULL;
tb->e2file = tb->f2file = NULL;
tb->ang = tb->e = tb->de = NULL;
tb->f = tb->df = tb->e2 = tb->f2 = NULL;
}
/* ---------------------------------------------------------------------- */
void AngleTable::free_table(Table *tb)
{
memory->destroy(tb->afile);
memory->destroy(tb->efile);
memory->destroy(tb->ffile);
memory->destroy(tb->e2file);
memory->destroy(tb->f2file);
memory->destroy(tb->ang);
memory->destroy(tb->e);
memory->destroy(tb->de);
memory->destroy(tb->f);
memory->destroy(tb->df);
memory->destroy(tb->e2);
memory->destroy(tb->f2);
}
/* ----------------------------------------------------------------------
read table file, only called by proc 0
------------------------------------------------------------------------- */
void AngleTable::read_table(Table *tb, char *file, char *keyword)
{
char line[MAXLINE];
// open file
FILE *fp = force->open_potential(file);
if (fp == NULL) {
char str[128];
sprintf(str,"Cannot open file %s",file);
error->one(FLERR,str);
}
// loop until section found with matching keyword
while (1) {
if (fgets(line,MAXLINE,fp) == NULL)
error->one(FLERR,"Did not find keyword in table file");
if (strspn(line," \t\n") == strlen(line)) continue; // blank line
if (line[0] == '#') continue; // comment
char *word = strtok(line," \t\n\r");
if (strcmp(word,keyword) == 0) 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);
memory->create(tb->afile,tb->ninput,"angle:afile");
memory->create(tb->efile,tb->ninput,"angle:efile");
memory->create(tb->ffile,tb->ninput,"angle:ffile");
// read a,e,f table values from file
int itmp;
fgets(line,MAXLINE,fp);
for (int i = 0; i < tb->ninput; i++) {
fgets(line,MAXLINE,fp);
sscanf(line,"%d %lg %lg %lg",
&itmp,&tb->afile[i],&tb->efile[i],&tb->ffile[i]);
}
fclose(fp);
}
/* ----------------------------------------------------------------------
build spline representation of e,f over entire range of read-in table
this function sets these values in e2file,f2file
------------------------------------------------------------------------- */
void AngleTable::spline_table(Table *tb)
{
memory->create(tb->e2file,tb->ninput,"angle:e2file");
memory->create(tb->f2file,tb->ninput,"angle:f2file");
double ep0 = - tb->ffile[0];
double epn = - tb->ffile[tb->ninput-1];
spline(tb->afile,tb->efile,tb->ninput,ep0,epn,tb->e2file);
if (tb->fpflag == 0) {
tb->fplo = (tb->ffile[1] - tb->ffile[0]) / (tb->afile[1] - tb->afile[0]);
tb->fphi = (tb->ffile[tb->ninput-1] - tb->ffile[tb->ninput-2]) /
(tb->afile[tb->ninput-1] - tb->afile[tb->ninput-2]);
}
double fp0 = tb->fplo;
double fpn = tb->fphi;
spline(tb->afile,tb->ffile,tb->ninput,fp0,fpn,tb->f2file);
}
/* ----------------------------------------------------------------------
compute a,e,f vectors from splined values
------------------------------------------------------------------------- */
void AngleTable::compute_table(Table *tb)
{
// delta = table spacing in angle for N-1 bins
int tlm1 = tablength-1;
tb->delta = MY_PI / tlm1;
tb->invdelta = 1.0/tb->delta;
tb->deltasq6 = tb->delta*tb->delta / 6.0;
// N-1 evenly spaced bins in angle from 0 to PI
// ang,e,f = value at lower edge of bin
// de,df values = delta values of e,f
// ang,e,f are N in length so de,df arrays can compute difference
memory->create(tb->ang,tablength,"angle:ang");
memory->create(tb->e,tablength,"angle:e");
memory->create(tb->de,tlm1,"angle:de");
memory->create(tb->f,tablength,"angle:f");
memory->create(tb->df,tlm1,"angle:df");
memory->create(tb->e2,tablength,"angle:e2");
memory->create(tb->f2,tablength,"angle:f2");
double a;
for (int i = 0; i < tablength; i++) {
a = i*tb->delta;
tb->ang[i] = a;
tb->e[i] = splint(tb->afile,tb->efile,tb->e2file,tb->ninput,a);
tb->f[i] = splint(tb->afile,tb->ffile,tb->f2file,tb->ninput,a);
}
for (int i = 0; i < tlm1; i++) {
tb->de[i] = tb->e[i+1] - tb->e[i];
tb->df[i] = tb->f[i+1] - tb->f[i];
}
double ep0 = - tb->f[0];
double epn = - tb->f[tlm1];
spline(tb->ang,tb->e,tablength,ep0,epn,tb->e2);
spline(tb->ang,tb->f,tablength,tb->fplo,tb->fphi,tb->f2);
}
/* ----------------------------------------------------------------------
extract attributes from parameter line in table section
format of line: N value FP fplo fphi EQ theta0
N is required, other params are optional
------------------------------------------------------------------------- */
void AngleTable::param_extract(Table *tb, char *line)
{
tb->ninput = 0;
tb->fpflag = 0;
tb->theta0 = 180.0;
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,"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);
tb->fplo *= (180.0/MY_PI)*(180.0/MY_PI);
tb->fphi *= (180.0/MY_PI)*(180.0/MY_PI);
} else if (strcmp(word,"EQ") == 0) {
word = strtok(NULL," \t\n\r\f");
tb->theta0 = atof(word);
} else {
error->one(FLERR,"Invalid keyword in angle table parameters");
}
word = strtok(NULL," \t\n\r\f");
}
if (tb->ninput == 0) error->one(FLERR,"Angle table parameters did not set N");
}
/* ----------------------------------------------------------------------
broadcast read-in table info from proc 0 to other procs
this function communicates these values in Table:
ninput,afile,efile,ffile,fpflag,fplo,fphi,theta0
------------------------------------------------------------------------- */
void AngleTable::bcast_table(Table *tb)
{
MPI_Bcast(&tb->ninput,1,MPI_INT,0,world);
int me;
MPI_Comm_rank(world,&me);
if (me > 0) {
memory->create(tb->afile,tb->ninput,"angle:afile");
memory->create(tb->efile,tb->ninput,"angle:efile");
memory->create(tb->ffile,tb->ninput,"angle:ffile");
}
MPI_Bcast(tb->afile,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->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);
}
MPI_Bcast(&tb->theta0,1,MPI_DOUBLE,0,world);
}
/* ----------------------------------------------------------------------
spline and splint routines modified from Numerical Recipes
------------------------------------------------------------------------- */
void AngleTable::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 AngleTable::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;
}
/* ----------------------------------------------------------------------
calculate potential u and force f at angle x
------------------------------------------------------------------------- */
void AngleTable::uf_lookup(int type, double x, double &u, double &f)
{
int itable;
double fraction,a,b;
Table *tb = &tables[tabindex[type]];
if (tabstyle == LINEAR) {
itable = static_cast<int> ( x * tb->invdelta);
fraction = (x - tb->ang[itable]) * tb->invdelta;
u = tb->e[itable] + fraction*tb->de[itable];
f = tb->f[itable] + fraction*tb->df[itable];
} else if (tabstyle == SPLINE) {
itable = static_cast<int> ( x * tb->invdelta);
fraction = (x - tb->ang[itable]) * tb->invdelta;
b = (x - tb->ang[itable]) * tb->invdelta;
a = 1.0 - b;
u = 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;
f = 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;
}
}
/* ----------------------------------------------------------------------
calculate potential u at angle x
------------------------------------------------------------------------- */
void AngleTable::u_lookup(int type, double x, double &u)
{
int itable;
double fraction,a,b;
Table *tb = &tables[tabindex[type]];
if (tabstyle == LINEAR) {
itable = static_cast<int> ( x * tb->invdelta);
fraction = (x - tb->ang[itable]) * tb->invdelta;
u = tb->e[itable] + fraction*tb->de[itable];
} else if (tabstyle == SPLINE) {
itable = static_cast<int> ( x * tb->invdelta);
fraction = (x - tb->ang[itable]) * tb->invdelta;
b = (x - tb->ang[itable]) * tb->invdelta;
a = 1.0 - b;
u = 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;
}
}

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