ICODE-ADC/lammps
4
0
Fork 0
Code Issues Pull Requests Actions Packages Projects Releases Wiki Activity

Improved rms force error estimate for coulomb tables. Now takes into consideration charge density, cutoff, number of atoms, etc.

Browse Source 
git-svn-id: svn://svn.icms.temple.edu/lammps-ro/trunk@8463 f3b2605a-c512-4ea7-a41b-209d697bcdaa
This commit is contained in:
pscrozi
2012-07-03 15:47:48 +00:00
parent 93adc50c75
commit 56ca4db42c
4 changed files with 21 additions and 20 deletions
Download Patch File Download Diff File Expand all files Collapse all files

6
src/KSPACE/ewald.cpp
View File

@ -174,9 +174,9 @@ void Ewald::init()
double lpry = rms(kymax,yprd,natoms,q2);
double lprz = rms(kzmax,zprd_slab,natoms,q2);
double lpr = sqrt(lprx*lprx + lpry*lpry + lprz*lprz) / sqrt(3.0);
double spr = 2.0*q2 * exp(-g_ewald*g_ewald*cutoff*cutoff) /
sqrt(natoms*cutoff*xprd*yprd*zprd_slab);
double tpr = estimate_table_accuracy(spr);
double q2_over_sqrt = q2 / sqrt(natoms*cutoff*xprd*yprd*zprd_slab);
double spr = 2.0 *q2_over_sqrt * exp(-g_ewald*g_ewald*cutoff*cutoff);
double tpr = estimate_table_accuracy(q2_over_sqrt,spr);
double accuracy = sqrt(lpr*lpr + spr*spr + tpr*tpr);
// stats

6
src/KSPACE/pppm.cpp
View File

@ -1089,9 +1089,9 @@ void PPPM::set_grid()
double lpry = rms(h_y,yprd,natoms,q2,acons);
double lprz = rms(h_z,zprd_slab,natoms,q2,acons);
double lpr = sqrt(lprx*lprx + lpry*lpry + lprz*lprz) / sqrt(3.0);
double spr = 2.0*q2 * exp(-g_ewald*g_ewald*cutoff*cutoff) /
sqrt(natoms*cutoff*xprd*yprd*zprd_slab);
double tpr = estimate_table_accuracy(spr);
double q2_over_sqrt = q2 / sqrt(natoms*cutoff*xprd*yprd*zprd_slab);
double spr = 2.0 *q2_over_sqrt * exp(-g_ewald*g_ewald*cutoff*cutoff);
double tpr = estimate_table_accuracy(q2_over_sqrt,spr);
double accuracy = sqrt(lpr*lpr + spr*spr + tpr*tpr);
// free local memory

27
src/kspace.cpp
View File

@ -129,30 +129,31 @@ void KSpace::ev_setup(int eflag, int vflag)
estimate the accuracy of the short-range coulomb tables
------------------------------------------------------------------------- */
double KSpace::estimate_table_accuracy(double spr)
double KSpace::estimate_table_accuracy(double q2_over_sqrt, double spr)
{
double table_accuracy = 0.0;
int nctb = force->pair->ncoultablebits;
if (nctb) {
double empirical_precision[17];
empirical_precision[6] = 2.12E-04;
empirical_precision[7] = 4.97E-05;
empirical_precision[8] = 1.24E-05;
empirical_precision[9] = 3.04E-06;
empirical_precision[10] = 8.51E-07;
empirical_precision[11] = 1.85E-07;
empirical_precision[12] = 5.87E-08;
empirical_precision[13] = 2.81E-08;
empirical_precision[14] = 2.20E-08;
empirical_precision[15] = 2.13E-08;
empirical_precision[16] = 2.11E-08;
empirical_precision[6] = 6.99E-03;
empirical_precision[7] = 1.78E-03;
empirical_precision[8] = 4.72E-04;
empirical_precision[9] = 1.17E-04;
empirical_precision[10] = 2.95E-05;
empirical_precision[11] = 7.41E-06;
empirical_precision[12] = 1.76E-06;
empirical_precision[13] = 9.28E-07;
empirical_precision[14] = 7.46E-07;
empirical_precision[15] = 7.32E-07;
empirical_precision[16] = 7.30E-07;
if (nctb <= 6) table_accuracy = empirical_precision[6];
else if (nctb <= 16) table_accuracy = empirical_precision[nctb];
else table_accuracy = empirical_precision[16];
table_accuracy *= two_charge_force;
table_accuracy *= q2_over_sqrt;
if (table_accuracy > spr)
error->warning(FLERR,"For better accuracy use 'pair_modify table 0'");
}
return table_accuracy;
}

2
src/kspace.h
View File

@ -70,7 +70,7 @@ class KSpace : protected Pointers {
int maxeatom,maxvatom;
void ev_setup(int, int);
double estimate_table_accuracy(double);
double estimate_table_accuracy(double, double);
};
}