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lammps/src/min_sd.cpp
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min_sd.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.
------------------------------------------------------------------------- */
#include <math.h>
#include <mpi.h>
#include "min_sd.h"
#include "atom.h"
#include "update.h"
#include "output.h"
#include "timer.h"
using namespace LAMMPS_NS;
// EPS_ENERGY = minimum normalization for energy tolerance
#define EPS_ENERGY 1.0e-8
// same as in other min classes
enum{MAXITER,MAXEVAL,ETOL,FTOL,DOWNHILL,ZEROALPHA,ZEROFORCE,ZEROQUAD};
/* ---------------------------------------------------------------------- */
MinSD::MinSD(LAMMPS *lmp) : MinLineSearch(lmp) {}
/* ----------------------------------------------------------------------
minimization via steepest descent
------------------------------------------------------------------------- */
int MinSD::iterate(int maxiter)
{
int i,m,n,fail,ntimestep;
double fdotf;
double *fatom,*hatom;
// initialize working vectors
for (i = 0; i < nvec; i++) h[i] = fvec[i];
if (nextra_atom)
for (m = 0; m < nextra_atom; m++) {
fatom = fextra_atom[m];
hatom = hextra_atom[m];
n = extra_nlen[m];
for (i = 0; i < n; i++) hatom[i] = fatom[i];
}
if (nextra_global)
for (i = 0; i < nextra_global; i++) hextra[i] = fextra[i];
for (int iter = 0; iter < maxiter; iter++) {
ntimestep = ++update->ntimestep;
niter++;
// line minimization along h from current position x
// h = downhill gradient direction
eprevious = ecurrent;
fail = (this->*linemin)(ecurrent,alpha_final);
if (fail) return fail;
// function evaluation criterion
if (neval >= update->max_eval) return MAXEVAL;
// energy tolerance criterion
if (fabs(ecurrent-eprevious) <
update->etol * 0.5*(fabs(ecurrent) + fabs(eprevious) + EPS_ENERGY))
return ETOL;
// force tolerance criterion
fdotf = fnorm_sqr();
if (fdotf < update->ftol*update->ftol) return FTOL;
// set new search direction h to f = -Grad(x)
for (i = 0; i < nvec; i++) h[i] = fvec[i];
if (nextra_atom)
for (m = 0; m < nextra_atom; m++) {
fatom = fextra_atom[m];
hatom = hextra_atom[m];
n = extra_nlen[m];
for (i = 0; i < n; i++) hatom[i] = fatom[i];
}
if (nextra_global)
for (i = 0; i < nextra_global; i++) hextra[i] = fextra[i];
// output for thermo, dump, restart files
if (output->next == ntimestep) {
timer->stamp();
output->write(ntimestep);
timer->stamp(Timer::OUTPUT);
}
}
return MAXITER;
}
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