107 lines
2.8 KiB
C++
107 lines
2.8 KiB
C++
/* ----------------------------------------------------------------------
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LAMMPS - Large-scale Atomic/Molecular Massively Parallel Simulator
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http://lammps.sandia.gov, Sandia National Laboratories
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Steve Plimpton, sjplimp@sandia.gov
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Copyright (2003) Sandia Corporation. Under the terms of Contract
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DE-AC04-94AL85000 with Sandia Corporation, the U.S. Government retains
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certain rights in this software. This software is distributed under
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the GNU General Public License.
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See the README file in the top-level LAMMPS directory.
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------------------------------------------------------------------------- */
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#include "math.h"
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#include "mpi.h"
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#include "min_sd.h"
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#include "atom.h"
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#include "update.h"
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#include "output.h"
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#include "timer.h"
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using namespace LAMMPS_NS;
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// EPS_ENERGY = minimum normalization for energy tolerance
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#define EPS_ENERGY 1.0e-8
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// same as in other min classes
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enum{MAXITER,MAXEVAL,ETOL,FTOL,DOWNHILL,ZEROALPHA,ZEROFORCE,ZEROQUAD};
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/* ---------------------------------------------------------------------- */
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MinSD::MinSD(LAMMPS *lmp) : Min(lmp) {}
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/* ----------------------------------------------------------------------
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minimization via steepest descent
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------------------------------------------------------------------------- */
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int MinSD::iterate(int n)
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{
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int i,fail,ntimestep;
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double dot,dotall;
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double *x = NULL;
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double *f = NULL;
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if (ndof) f = atom->f[0];
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for (i = 0; i < ndof; i++) h[i] = f[i];
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if (nextra)
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for (i = 0; i < nextra; i++)
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hextra[i] = fextra[i];
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neval = 0;
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for (niter = 0; niter < n; niter++) {
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ntimestep = ++update->ntimestep;
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// line minimization along direction h from current atom->x
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eprevious = ecurrent;
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if (ndof) x = atom->x[0];
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fail = (this->*linemin)(ndof,x,h,x0,ecurrent,dmax,alpha_final,neval);
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if (fail) return fail;
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// function evaluation criterion
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if (neval >= update->max_eval) return MAXEVAL;
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// energy tolerance criterion
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if (fabs(ecurrent-eprevious) <
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update->etol * 0.5*(fabs(ecurrent) + fabs(eprevious) + EPS_ENERGY))
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return ETOL;
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// force tolerance criterion
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if (ndof) f = atom->f[0];
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dot = 0.0;
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for (i = 0; i < ndof; i++) dot += f[i]*f[i];
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MPI_Allreduce(&dot,&dotall,1,MPI_DOUBLE,MPI_SUM,world);
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if (nextra)
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for (i = 0; i < nextra; i++)
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dotall += fextra[i]*fextra[i];
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if (dotall < update->ftol * update->ftol) return FTOL;
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// set new search direction h to f = -Grad(x)
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for (i = 0; i < ndof; i++) h[i] = f[i];
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if (nextra)
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for (i = 0; i < nextra; i++)
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hextra[i] = fextra[i];
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// output for thermo, dump, restart files
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if (output->next == ntimestep) {
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timer->stamp();
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output->write(ntimestep);
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timer->stamp(TIME_OUTPUT);
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}
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}
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return MAXITER;
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}
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