Commit 91993b23 authored by Axel Kohlmeyer's avatar Axel Kohlmeyer
Browse files

avoid division by zero in PPPM for empty and uncharged systems. require kspace_modify gewald

parent 5ecc3ce3

src/KOKKOS/pppm_kokkos.cpp

+3 −0
Original line number Diff line number Diff line
@@ -969,6 +969,8 @@ void PPPMKokkos<DeviceType>::set_grid_global() 
  if (!gewaldflag) {

    if (accuracy <= 0.0)

      error->all(FLERR,"KSpace accuracy must be > 0");

    if (q2 == 0.0)

      error->all(FLERR,"Must use 'kspace_modify gewald' for uncharged system");

    g_ewald = accuracy*sqrt(natoms*cutoff*xprd*yprd*zprd) / (2.0*q2);

    if (g_ewald >= 1.0) g_ewald = (1.35 - 0.15*log(accuracy))/cutoff;

    else g_ewald = sqrt(-log(g_ewald)) / cutoff;
@@ -1179,6 +1181,7 @@ double PPPMKokkos<DeviceType>::final_accuracy() 
  double yprd = domain->yprd;

  double zprd = domain->zprd;

  bigint natoms = atomKK->natoms;

  if (natoms == 0) natoms = 1; // avoid division by zero



  double df_kspace = compute_df_kspace();

  double q2_over_sqrt = q2 / sqrt(natoms*cutoff*xprd*yprd*zprd);

src/KSPACE/pppm.cpp

+3 −0
Original line number Diff line number Diff line
@@ -1004,6 +1004,8 @@ void PPPM::set_grid_global() 
  if (!gewaldflag) {

    if (accuracy <= 0.0)

      error->all(FLERR,"KSpace accuracy must be > 0");

    if (q2 == 0.0)

      error->all(FLERR,"Must use kspace_modify gewald for uncharged system");

    g_ewald = accuracy*sqrt(natoms*cutoff*xprd*yprd*zprd) / (2.0*q2);

    if (g_ewald >= 1.0) g_ewald = (1.35 - 0.15*log(accuracy))/cutoff;

    else g_ewald = sqrt(-log(g_ewald)) / cutoff;
@@ -1346,6 +1348,7 @@ double PPPM::final_accuracy() 
  double yprd = domain->yprd;

  double zprd = domain->zprd;

  bigint natoms = atom->natoms;

  if (natoms == 0) natoms = 1; // avoid division by zero



  double df_kspace = compute_df_kspace();

  double q2_over_sqrt = q2 / sqrt(natoms*cutoff*xprd*yprd*zprd);

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