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git-svn-id: svn://svn.icms.temple.edu/lammps-ro/trunk@7858 f3b2605a-c512-4ea7-a41b-209d697bcdaa

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This commit is contained in:
sjplimp
2012-02-28 19:52:12 +00:00
parent 00944a2b95
commit 6a544be9cf
7 changed files with 1159 additions and 813 deletions
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43
src/KSPACE/pppm.cpp
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@ -60,8 +60,8 @@ PPPM::PPPM(LAMMPS *lmp, int narg, char **arg) : KSpace(lmp, narg, arg)
{
if (narg < 1) error->all(FLERR,"Illegal kspace_style pppm command");
precision = atof(arg[0]);
accuracy_relative = atof(arg[0]);
nfactors = 3;
factors = new int[nfactors];
factors[0] = 2;
@ -222,6 +222,11 @@ void PPPM::init()
error->warning(FLERR,str);
}
// set accuracy (force units) from accuracy_relative or accuracy_absolute
if (accuracy_absolute >= 0.0) accuracy = accuracy_absolute;
else accuracy = accuracy_relative * two_charge_force;
// setup FFT grid resolution and g_ewald
// normally one iteration thru while loop is all that is required
// if grid stencil extends beyond neighbor proc, reduce order and try again
@ -229,7 +234,6 @@ void PPPM::init()
int iteration = 0;
while (order > 0) {
if (iteration && me == 0)
error->warning(FLERR,"Reducing PPPM order b/c stencil extends "
"beyond neighbor processor");
@ -970,9 +974,7 @@ void PPPM::set_grid()
acons[7][5] = 1755948832039.0 / 36229939200000.0;
acons[7][6] = 4887769399.0 / 37838389248.0;
//double q2 = qsqsum * force->qqrd2e / force->dielectric;
double q2 = qsqsum / force->dielectric;
bigint natoms = atom->natoms;
double q2 = qsqsum * force->qqrd2e / force->dielectric;
// use xprd,yprd,zprd even if triclinic so grid size is the same
// adjust z dimension for 2d slab PPPM
@ -984,20 +986,21 @@ void PPPM::set_grid()
double zprd_slab = zprd*slab_volfactor;
// make initial g_ewald estimate
// based on desired error and real space cutoff
// based on desired accuracy and real space cutoff
// fluid-occupied volume used to estimate real-space error
// zprd used rather than zprd_slab
double h_x,h_y,h_z;
bigint natoms = atom->natoms;
if (!gewaldflag)
g_ewald = sqrt(-log(precision*sqrt(natoms*cutoff*xprd*yprd*zprd) /
g_ewald = sqrt(-log(accuracy*sqrt(natoms*cutoff*xprd*yprd*zprd) /
(2.0*q2))) / cutoff;
// set optimal nx_pppm,ny_pppm,nz_pppm based on order and precision
// set optimal nx_pppm,ny_pppm,nz_pppm based on order and accuracy
// nz_pppm uses extended zprd_slab instead of zprd
// h = 1/g_ewald is upper bound on h such that h*g_ewald <= 1
// reduce it until precision target is met
// reduce it until accuracy target is met
if (!gridflag) {
double err;
@ -1008,21 +1011,21 @@ void PPPM::set_grid()
nz_pppm = static_cast<int> (zprd_slab/h_z + 1);
err = rms(h_x,xprd,natoms,q2,acons);
while (err > precision) {
while (err > accuracy) {
err = rms(h_x,xprd,natoms,q2,acons);
nx_pppm++;
h_x = xprd/nx_pppm;
}
err = rms(h_y,yprd,natoms,q2,acons);
while (err > precision) {
while (err > accuracy) {
err = rms(h_y,yprd,natoms,q2,acons);
ny_pppm++;
h_y = yprd/ny_pppm;
}
err = rms(h_z,zprd_slab,natoms,q2,acons);
while (err > precision) {
while (err > accuracy) {
err = rms(h_z,zprd_slab,natoms,q2,acons);
nz_pppm++;
h_z = zprd_slab/nz_pppm;
@ -1067,7 +1070,7 @@ void PPPM::set_grid()
}
}
// final RMS precision
// final RMS accuracy
double lprx = rms(h_x,xprd,natoms,q2,acons);
double lpry = rms(h_y,yprd,natoms,q2,acons);
@ -1092,14 +1095,18 @@ void PPPM::set_grid()
fprintf(screen," G vector (1/distance)= %g\n",g_ewald);
fprintf(screen," grid = %d %d %d\n",nx_pppm,ny_pppm,nz_pppm);
fprintf(screen," stencil order = %d\n",order);
fprintf(screen," RMS precision = %g\n",MAX(lpr,spr));
fprintf(screen," absolute RMS force accuracy = %g\n",MAX(lpr,spr));
fprintf(screen," relative force accuracy = %g\n",
MAX(lpr,spr)/two_charge_force);
fprintf(screen," using %s precision FFTs\n",fft_prec);
}
if (logfile) {
fprintf(logfile," G vector (1/distance) = %g\n",g_ewald);
fprintf(logfile," grid = %d %d %d\n",nx_pppm,ny_pppm,nz_pppm);
fprintf(logfile," stencil order = %d\n",order);
fprintf(logfile," RMS precision = %g\n",MAX(lpr,spr));
fprintf(logfile," absolute RMS force accuracy = %g\n",MAX(lpr,spr));
fprintf(logfile," relative force accuracy = %g\n",
MAX(lpr,spr)/two_charge_force);
fprintf(logfile," using %s precision FFTs\n",fft_prec);
}
}
@ -1128,7 +1135,7 @@ int PPPM::factorable(int n)
}
/* ----------------------------------------------------------------------
compute RMS precision for a dimension
compute RMS accuracy for a dimension
------------------------------------------------------------------------- */
double PPPM::rms(double h, double prd, bigint natoms,
@ -1143,7 +1150,7 @@ double PPPM::rms(double h, double prd, bigint natoms,
}
/* ----------------------------------------------------------------------
compute difference in real-space and kspace RMS precision
compute difference in real-space and KSpace RMS accuracy
------------------------------------------------------------------------- */
double PPPM::diffpr(double h_x, double h_y, double h_z, double q2,