From 3ee6203e5a6c79c82217437fa071bd1781c381f9 Mon Sep 17 00:00:00 2001
From: Steve Plimpton <sjplimp@sandia.gov>
Date: Wed, 18 Nov 2020 12:51:24 -0700
Subject: [PATCH] simplification to Pair::ev_setup()

---
 src/pair.cpp | 39 ++++++++++++++-------------------------
 1 file changed, 14 insertions(+), 25 deletions(-)

diff --git a/src/pair.cpp b/src/pair.cpp
index 2cb0b2b210..bf43168407 100644
--- a/src/pair.cpp
+++ b/src/pair.cpp
@@ -779,21 +779,19 @@ void Pair::del_tally_callback(Compute *ptr)
    setup for energy, virial computation
    see integrate::ev_set() for bitwise settings of eflag/vflag
    set the following flags, values are otherwise 0:
-     evflag       != 0 if any bits of eflag or vflag are set
      eflag_global != 0 if ENERGY_GLOBAL bit of eflag set
      eflag_atom   != 0 if ENERGY_ATOM bit of eflag set
      eflag_either != 0 if eflag_global or eflag_atom is set
-     vflag_global = VIRIAL_PAIR if VIRIAL_PAIR bit of vflag set
-     vflag_global = VIRIAL_FDOTR if VIRIAL_FDOTR bit of vflag set
-       this setting also sets vflag_dotr = 1 if pair style supports it,
-       which unsets vflag_global and can also thus change other flags,
-       see logic at end of method
+     vflag_global != 0 if VIRIAL_PAIR bit of vflag set
+     vflag_global != 0 if VIRIAL_FDOTR bit of vflag is set but no_virial_fdotr = 1
+     vflag_fdotr  != 0 if VIRIAL_FDOTR bit of vflag set and no_virial_fdotr = 0
      vflag_atom   != 0 if VIRIAL_ATOM bit of vflag set
      vflag_atom   != 0 if VIRIAL_CENTROID bit of vflag set
                        and centroidstressflag != CENTROID_AVAIL
      cvflag_atom  != 0 if VIRIAL_CENTROID bit of vflag set
                        and centroidstressflag = CENTROID_AVAIL
      vflag_either != 0 if any of vflag_global, vflag_atom, cvflag_atom is set
+     evflag       != 0 if eflag_either or vflag_either is set
    centroidstressflag is set by the pair style to one of these values:
      CENTROID_SAME = same as two-body stress
      CENTROID_AVAIL = different and implemented
@@ -804,20 +802,20 @@ void Pair::ev_setup(int eflag, int vflag, int alloc)
 {
   int i,n;
 
-  evflag = 1;
-
   eflag_either = eflag;
   eflag_global = eflag & ENERGY_GLOBAL;
   eflag_atom = eflag & ENERGY_ATOM;
-
-  vflag_global = vflag & (VIRIAL_PAIR | VIRIAL_FDOTR);
+  
+  vflag_global = vflag & VIRIAL_PAIR;
+  if (vflag & VIRIAL_FDOTR && no_virial_fdotr_compute == 1) vflag_global = 1;
+  if (vflag & VIRIAL_FDOTR && no_virial_fdotr_compute == 0) vflag_fdotr = 1;
   vflag_atom = vflag & VIRIAL_ATOM;
-  if (vflag & VIRIAL_CENTROID && centroidstressflag != CENTROID_AVAIL)
-    vflag_atom = 1;
-  if (vflag & VIRIAL_CENTROID && centroidstressflag == CENTROID_AVAIL)
-    cvflag_atom = 1;
+  if (vflag & VIRIAL_CENTROID && centroidstressflag != CENTROID_AVAIL) vflag_atom = 1;
+  if (vflag & VIRIAL_CENTROID && centroidstressflag == CENTROID_AVAIL) cvflag_atom = 1;
   vflag_either = vflag_global || vflag_atom || cvflag_atom;
 
+  evflag = eflag_either || vflag_either;
+
   // reallocate per-atom arrays if necessary
 
   if (eflag_atom && atom->nmax > maxeatom) {
@@ -882,17 +880,6 @@ void Pair::ev_setup(int eflag, int vflag, int alloc)
     }
   }
 
-  // if vflag_global = VIRIAL_FDOTR and pair::compute() calls virial_fdotr_compute()
-  // compute global virial via (F dot r) instead of via pairwise summation
-  // unset other flags as appropriate
-
-  if (vflag_global == VIRIAL_FDOTR && no_virial_fdotr_compute == 0) {
-    vflag_fdotr = 1;
-    vflag_global = 0;
-    if (!vflag_atom == 0 && !cvflag_atom) vflag_either = 0;
-    if (!vflag_either == 0 && !eflag_either) evflag = 0;
-  } else vflag_fdotr = 0;
-
   // run ev_setup option for USER-TALLY computes
 
   if (num_tally_compute > 0) {
@@ -1575,6 +1562,8 @@ void Pair::virial_fdotr_compute()
   double **x = atom->x;
   double **f = atom->f;
 
+  for (int i = 0; i < 6; i++) virial[i] = 0.0;
+
   // sum over force on all particles including ghosts
 
   if (neighbor->includegroup == 0) {