add KSpace style zero to KSPACE and zero2 as plugin demo

2025-01-29 15:39:53 -05:00
parent c4d11a7871
commit e3dd2790f9
6 changed files with 346 additions and 0 deletions
--- a/examples/plugins/kspace_zero2.cpp
+++ b/examples/plugins/kspace_zero2.cpp
@ -0,0 +1,117 @@
+/* ----------------------------------------------------------------------
+   LAMMPS - Large-scale Atomic/Molecular Massively Parallel Simulator
+   https://www.lammps.org/, Sandia National Laboratories
+   LAMMPS development team: developers@lammps.org
+
+   Copyright (2003) Sandia Corporation.  Under the terms of Contract
+   DE-AC04-94AL85000 with Sandia Corporation, the U.S. Government retains
+   certain rights in this software.  This software is distributed under
+   the GNU General Public License.
+
+   See the README file in the top-level LAMMPS directory.
+------------------------------------------------------------------------- */
+
+/* ----------------------------------------------------------------------
+   Contributing author: Axel Kohlmeyer (Temple U)
+------------------------------------------------------------------------- */
+
+#include "kspace_zero2.h"
+
+#include "atom.h"
+#include "comm.h"
+#include "domain.h"
+#include "error.h"
+#include "force.h"
+#include "pair.h"
+
+#include <cstring>
+
+using namespace LAMMPS_NS;
+
+/* ---------------------------------------------------------------------- */
+
+KSpaceZero2::KSpaceZero2(LAMMPS *lmp) : KSpace(lmp)
+{
+  ewaldflag = 1;
+  pppmflag = 1;
+  msmflag = 1;
+  dispersionflag = 1;
+  tip4pflag = 1;
+  dipoleflag = 1;
+  spinflag = 1;
+}
+
+KSpaceZero2::~KSpaceZero2()
+{
+  fprintf(stderr, "In destructor for KSpace zero2. This = %p\n", this);
+}
+
+/* ---------------------------------------------------------------------- */
+
+void KSpaceZero2::settings(int narg, char **arg)
+{
+  if (narg != 1) error->all(FLERR, "Illegal kspace_style {} command", force->kspace_style);
+
+  accuracy_relative = fabs(utils::numeric(FLERR, arg[0], false, lmp));
+  if (accuracy_relative > 1.0)
+    error->all(FLERR, "Invalid relative accuracy {:g} for kspace_style {}", accuracy_relative,
+               force->kspace_style);
+  if ((narg != 0) && (narg != 1)) error->all(FLERR, "Illegal kspace_style command");
+}
+
+/* ---------------------------------------------------------------------- */
+
+void KSpaceZero2::init()
+{
+  if (comm->me == 0) utils::logmesg(lmp, "Dummy KSpace initialization ...\n");
+
+  // error checks
+
+  if (force->pair == nullptr) error->all(FLERR, "KSpace solver requires a pair style");
+  if (!atom->q_flag) error->all(FLERR, "KSpace style zero2 requires atom attribute q");
+
+  // compute two charge force
+
+  two_charge();
+
+  int itmp;
+  auto p_cutoff = (double *) force->pair->extract("cut_coul", itmp);
+  if (p_cutoff == nullptr) error->all(FLERR, "KSpace style is incompatible with Pair style");
+  double cutoff = *p_cutoff;
+
+  qsum_qsq();
+
+  accuracy = accuracy_relative * two_charge_force;
+
+  // make initial g_ewald estimate
+  // based on desired accuracy and real space cutoff
+  // fluid-occupied volume used to estimate real-space error
+  // zprd used rather than zprd_slab
+
+  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(atom->natoms * cutoff * domain->xprd * domain->yprd * domain->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;
+  }
+
+  if (comm->me == 0) std::string mesg = fmt::format("  G vector (1/distance) = {:.8g}\n", g_ewald);
+}
+
+/* ---------------------------------------------------------------------- */
+
+void KSpaceZero2::setup()
+{
+  if (comm->me == 0) utils::logmesg(lmp, "Dummy KSpace setup\n");
+}
+
+/* ---------------------------------------------------------------------- */
+
+void KSpaceZero2::compute(int eflag, int vflag)
+{
+  ev_init(eflag, vflag);
+}