238 lines
6.4 KiB
C++
238 lines
6.4 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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/* ----------------------------------------------------------------------
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Contributing author: Ray Shan (Sandia)
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------------------------------------------------------------------------- */
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#include <cmath>
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#include <cstdio>
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#include <cstdlib>
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#include <cstring>
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#include "fix_qeq_shielded.h"
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#include "atom.h"
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#include "comm.h"
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#include "domain.h"
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#include "neighbor.h"
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#include "neigh_list.h"
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#include "neigh_request.h"
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#include "update.h"
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#include "force.h"
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#include "group.h"
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#include "kspace.h"
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#include "respa.h"
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#include "memory.h"
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#include "error.h"
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using namespace LAMMPS_NS;
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/* ---------------------------------------------------------------------- */
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FixQEqShielded::FixQEqShielded(LAMMPS *lmp, int narg, char **arg) :
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FixQEq(lmp, narg, arg) {}
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/* ---------------------------------------------------------------------- */
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void FixQEqShielded::init()
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{
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if (!atom->q_flag)
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error->all(FLERR,"Fix qeq/shielded requires atom attribute q");
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ngroup = group->count(igroup);
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if (ngroup == 0) error->all(FLERR,"Fix qeq/shielded group has no atoms");
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int irequest = neighbor->request(this,instance_me);
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neighbor->requests[irequest]->pair = 0;
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neighbor->requests[irequest]->fix = 1;
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neighbor->requests[irequest]->half = 0;
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neighbor->requests[irequest]->full = 1;
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int ntypes = atom->ntypes;
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memory->create(shld,ntypes+1,ntypes+1,"qeq:shielding");
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init_shielding();
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int i;
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for (i = 1; i <= ntypes; i++) {
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if (gamma[i] == 0.0)
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error->all(FLERR,"Invalid param file for fix qeq/shielded");
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}
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if (strstr(update->integrate_style,"respa"))
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nlevels_respa = ((Respa *) update->integrate)->nlevels;
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}
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/* ---------------------------------------------------------------------- */
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void FixQEqShielded::init_shielding()
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{
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int i,j;
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double d7, swa2, swa3, swb2, swb3;
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int ntypes = atom->ntypes;
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for( i = 1; i <= ntypes; ++i )
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for( j = 1; j <= ntypes; ++j )
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shld[i][j] = pow( gamma[i] * gamma[j], -1.5 );
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if (fabs(swa) > 0.01 && comm->me == 0)
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error->warning(FLERR,"Fix qeq has non-zero lower Taper radius cutoff");
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if (swb < 0)
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error->all(FLERR, "Fix qeq has negative upper Taper radius cutoff");
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else if (swb < 5 && comm->me == 0)
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error->warning(FLERR,"Fix qeq has very low Taper radius cutoff");
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d7 = pow( swb - swa, 7 );
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swa2 = swa*swa;
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swa3 = swa2*swa;
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swb2 = swb*swb;
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swb3 = swb2*swb;
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Tap[7] = 20.0 / d7;
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Tap[6] = -70.0 * (swa + swb) / d7;
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Tap[5] = 84.0 * (swa2 + 3.0*swa*swb + swb2) / d7;
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Tap[4] = -35.0 * (swa3 + 9.0*swa2*swb + 9.0*swa*swb2 + swb3 ) / d7;
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Tap[3] = 140.0 * (swa3*swb + 3.0*swa2*swb2 + swa*swb3 ) / d7;
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Tap[2] =-210.0 * (swa3*swb2 + swa2*swb3) / d7;
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Tap[1] = 140.0 * swa3 * swb3 / d7;
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Tap[0] = (-35.0*swa3*swb2*swb2 + 21.0*swa2*swb3*swb2 -
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7.0*swa*swb3*swb3 + swb3*swb3*swb ) / d7;
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}
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/* ---------------------------------------------------------------------- */
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void FixQEqShielded::pre_force(int vflag)
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{
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if (update->ntimestep % nevery) return;
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nlocal = atom->nlocal;
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if( atom->nmax > nmax ) reallocate_storage();
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if( nlocal > n_cap*DANGER_ZONE || m_fill > m_cap*DANGER_ZONE )
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reallocate_matrix();
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init_matvec();
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matvecs = CG(b_s, s); // CG on s - parallel
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matvecs += CG(b_t, t); // CG on t - parallel
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calculate_Q();
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if (force->kspace) force->kspace->qsum_qsq();
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}
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/* ---------------------------------------------------------------------- */
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void FixQEqShielded::init_matvec()
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{
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compute_H();
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int inum, ii, i;
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int *ilist;
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inum = list->inum;
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ilist = list->ilist;
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for( ii = 0; ii < inum; ++ii ) {
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i = ilist[ii];
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if (atom->mask[i] & groupbit) {
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Hdia_inv[i] = 1. / eta[ atom->type[i] ];
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b_s[i] = -( chi[atom->type[i]] + chizj[i] );
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b_t[i] = -1.0;
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t[i] = t_hist[i][2] + 3 * ( t_hist[i][0] - t_hist[i][1] );
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s[i] = 4*(s_hist[i][0]+s_hist[i][2])-(6*s_hist[i][1]+s_hist[i][3]);
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}
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}
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pack_flag = 2;
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comm->forward_comm_fix(this); //Dist_vector( s );
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pack_flag = 3;
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comm->forward_comm_fix(this); //Dist_vector( t );
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}
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/* ---------------------------------------------------------------------- */
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void FixQEqShielded::compute_H()
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{
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int inum, jnum, *ilist, *jlist, *numneigh, **firstneigh;
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int i, j, ii, jj;
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double **x;
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double dx, dy, dz, r_sqr, r;
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int *type = atom->type;
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x = atom->x;
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int *mask = atom->mask;
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inum = list->inum;
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ilist = list->ilist;
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numneigh = list->numneigh;
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firstneigh = list->firstneigh;
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// fill in the H matrix
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m_fill = 0;
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r_sqr = 0;
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for( ii = 0; ii < inum; ii++ ) {
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i = ilist[ii];
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if (mask[i] & groupbit) {
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jlist = firstneigh[i];
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jnum = numneigh[i];
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H.firstnbr[i] = m_fill;
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for( jj = 0; jj < jnum; jj++ ) {
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j = jlist[jj];
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j &= NEIGHMASK;
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dx = x[j][0] - x[i][0];
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dy = x[j][1] - x[i][1];
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dz = x[j][2] - x[i][2];
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r_sqr = dx*dx + dy*dy + dz*dz;
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if (r_sqr <= cutoff_sq) {
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H.jlist[m_fill] = j;
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r = sqrt(r_sqr);
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H.val[m_fill] = 0.5 * calculate_H( r, shld[type[i]][type[j]] );
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m_fill++;
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}
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}
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H.numnbrs[i] = m_fill - H.firstnbr[i];
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}
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}
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if (m_fill >= H.m) {
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char str[128];
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sprintf(str,"H matrix size has been exceeded: m_fill=%d H.m=%d\n",
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m_fill, H.m );
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error->warning(FLERR,str);
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error->all(FLERR,"Fix qeq/shielded has insufficient QEq matrix size");
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}
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}
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/* ---------------------------------------------------------------------- */
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double FixQEqShielded::calculate_H( double r, double gamma )
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{
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double Taper, denom;
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Taper = Tap[7] * r + Tap[6];
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Taper = Taper * r + Tap[5];
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Taper = Taper * r + Tap[4];
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Taper = Taper * r + Tap[3];
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Taper = Taper * r + Tap[2];
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Taper = Taper * r + Tap[1];
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Taper = Taper * r + Tap[0];
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denom = r * r * r + gamma;
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denom = pow(denom,0.3333333333333);
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return Taper * EV_TO_KCAL_PER_MOL / denom;
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}
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