git-svn-id: svn://svn.icms.temple.edu/lammps-ro/trunk@11646 f3b2605a-c512-4ea7-a41b-209d697bcdaa

src/GPU/pair_lj_cut_coul_msm_gpu.cpp

@@ -136,6 +136,9 @@ void PairLJCutCoulMSMGPU::init_style()
   if (force->newton_pair) 
     error->all(FLERR,"Cannot use newton pair with lj/cut/coul/msm/gpu pair style");
 
+  if (force->kspace->scalar_pressure_flag)
+    error->all(FLERR,"Must use 'kspace_modify pressure/scalar no' with GPU MSM Pair styles");
+
   // Repeat cutsq calculation because done after call to init_style
   double maxcut = -1.0;
   double cut;

src/GPU/pair_lj_cut_coul_msm_gpu.h

@@ -56,4 +56,8 @@ E: Cannot use newton pair with lj/cut/coul/msm/gpu pair style
 
 Self-explanatory.
 
+E: Must use 'kspace_modify pressure/scalar no' with GPU MSM Pair styles
+
+The kspace scalar pressure option is not (yet) compatible with GPU MSM Pair styles.
+
 */

src/KSPACE/msm.cpp

@@ -100,6 +100,7 @@ MSM::MSM(LAMMPS *lmp, int narg, char **arg) : KSpace(lmp, narg, arg)
   levels = 0;
 
   peratom_allocate_flag = 0;
+  scalar_pressure_flag = 1;
 
   order = 10;
 }
@@ -416,7 +417,7 @@ void MSM::setup()
   } else {
     get_g_direct();
     if (domain->nonperiodic) get_g_direct_top(levels-1);
-    if (vflag_either) {
+    if (vflag_either && !scalar_pressure_flag) {
       get_virial_direct();
       if (domain->nonperiodic) get_virial_direct_top(levels-1);
     }
@@ -463,6 +464,19 @@ void MSM::compute(int eflag, int vflag)
   else evflag = evflag_atom = eflag_global = vflag_global =
     eflag_atom = vflag_atom = eflag_either = vflag_either = 0;
 
+  if (scalar_pressure_flag && vflag_either) {
+    if (vflag_atom)
+      error->all(FLERR,"Must use 'kspace_modify pressure/scalar no' to obtain "
+        "per-atom virial with kspace_style MSM");
+
+    // must switch on global energy computation if not already on
+
+    if (eflag == 0 || eflag == 2) {
+      eflag++;
+      ev_setup(eflag,vflag);
+    }
+  }
+
   // invoke allocate_peratom() if needed for first time
 
   if (vflag_atom && !peratom_allocate_flag) {
@@ -588,12 +602,17 @@ void MSM::compute(int eflag, int vflag)
 
   // total long-range virial
 
-  if (vflag_global) {
+  if (vflag_global && !scalar_pressure_flag) {
     double virial_all[6];
     MPI_Allreduce(virial,virial_all,6,MPI_DOUBLE,MPI_SUM,world);
     for (i = 0; i < 6; i++) virial[i] = 0.5*qscale*virial_all[i];
   }
 
+  // fast compute of scalar pressure (if requested)
+
+  if (scalar_pressure_flag && vflag_global)
+    for (i = 0; i < 3; i++) virial[i] = energy/3.0;
+
   // per-atom energy/virial
   // energy includes self-energy correction
 
@@ -1588,7 +1607,7 @@ void MSM::direct(int n)
         qtmp = qgridn[icz][icy][icx]; // charge on center grid point
 
         esum = 0.0;
-        if (vflag_either)
+        if (vflag_either && !scalar_pressure_flag)
           v0sum = v1sum = v2sum = v3sum = v4sum = v5sum = 0.0;
 
         // use hemisphere to avoid double computation of pair-wise
@@ -1612,7 +1631,7 @@ void MSM::direct(int n)
               esum += gtmp * qtmp2;
               ekj[ii] += gtmp * qtmp;
 
-              if (vflag_either) {
+              if (vflag_either && !scalar_pressure_flag) {
                 v0sum += v0_directn[k] * qtmp2;
                 v1sum += v1_directn[k] * qtmp2;
                 v2sum += v2_directn[k] * qtmp2;
@@ -1644,7 +1663,7 @@ void MSM::direct(int n)
             esum += gtmp * qtmp2;
             ekj[ii] += gtmp * qtmp;
 
-            if (vflag_either) {
+            if (vflag_either && !scalar_pressure_flag) {
               v0sum += v0_directn[k] * qtmp2;
               v1sum += v1_directn[k] * qtmp2;
               v2sum += v2_directn[k] * qtmp2;
@@ -1675,7 +1694,7 @@ void MSM::direct(int n)
           esum += gtmp * qtmp2;
           ekj[ii] += gtmp * qtmp;
 
-          if (vflag_either) {
+          if (vflag_either && !scalar_pressure_flag) {
             v0sum += v0_directn[k] * qtmp2;
             v1sum += v1_directn[k] * qtmp2;
             v2sum += v2_directn[k] * qtmp2;
@@ -1717,7 +1736,7 @@ void MSM::direct(int n)
         if (evflag) {
           qtmp = qgridn[icz][icy][icx];
           if (eflag_global) energy += 2.0 * esum * qtmp;
-          if (vflag_global) {
+          if (vflag_global && !scalar_pressure_flag) {
             virial[0] += 2.0 * v0sum * qtmp;
             virial[1] += 2.0 * v1sum * qtmp;
             virial[2] += 2.0 * v2sum * qtmp;
@@ -1947,7 +1966,7 @@ void MSM::direct_top(int n)
         qtmp = qgridn[icz][icy][icx];
 
         esum = 0.0;
-        if (vflag_either)
+        if (vflag_either && !scalar_pressure_flag)
           v0sum = v1sum = v2sum = v3sum = v4sum = v5sum = 0.0;
 
         // use hemisphere to avoid double computation of pair-wise
@@ -1971,7 +1990,7 @@ void MSM::direct_top(int n)
               esum += gtmp * qtmp2;
               ekj[ii] += gtmp * qtmp;
 
-              if (vflag_either) {
+              if (vflag_either && !scalar_pressure_flag) {
                 v0sum += v0_direct_top[k] * qtmp2;
                 v1sum += v1_direct_top[k] * qtmp2;
                 v2sum += v2_direct_top[k] * qtmp2;
@@ -2003,7 +2022,7 @@ void MSM::direct_top(int n)
             esum += gtmp * qtmp2;
             ekj[ii] += gtmp * qtmp;
 
-            if (vflag_either) {
+            if (vflag_either && !scalar_pressure_flag) {
               v0sum += v0_direct_top[k] * qtmp2;
               v1sum += v1_direct_top[k] * qtmp2;
               v2sum += v2_direct_top[k] * qtmp2;
@@ -2034,7 +2053,7 @@ void MSM::direct_top(int n)
           esum += gtmp * qtmp2;
           ekj[ii] += gtmp * qtmp;
 
-          if (vflag_either) {
+          if (vflag_either && !scalar_pressure_flag) {
             v0sum += v0_direct_top[k] * qtmp2;
             v1sum += v1_direct_top[k] * qtmp2;
             v2sum += v2_direct_top[k] * qtmp2;
@@ -2057,7 +2076,7 @@ void MSM::direct_top(int n)
         esum += 0.5 * gtmp * qtmp;
         egridn[icz][icy][icx] += 0.5 * gtmp * qtmp;
 
-        if (vflag_either) {
+        if (vflag_either && !scalar_pressure_flag) {
           v0sum += v0_direct_top[k] * qtmp;
           v1sum += v1_direct_top[k] * qtmp;
           v2sum += v2_direct_top[k] * qtmp;
@@ -2084,7 +2103,7 @@ void MSM::direct_top(int n)
         if (evflag) {
           qtmp = qgridn[icz][icy][icx];
           if (eflag_global) energy += 2.0 * esum * qtmp;
-          if (vflag_global) {
+          if (vflag_global && !scalar_pressure_flag) {
             virial[0] += 2.0 * v0sum * qtmp;
             virial[1] += 2.0 * v1sum * qtmp;
             virial[2] += 2.0 * v2sum * qtmp;

src/KSPACE/msm.h

@@ -217,6 +217,11 @@ The global MSM grid is larger than OFFSET in one or more dimensions.
 OFFSET is currently set to 16384.  You likely need to decrease the
 requested accuracy.
 
+E: Must use 'kspace_modify pressure/scalar no' to obtain per-atom virial
+with kspace_style MSM
+
+The kspace scalar pressure option cannot be used to obtain per-atom virial.
+
 E: Out of range atoms - cannot compute MSM
 
 One or more atoms are attempting to map their charge to a MSM grid point 

src/KSPACE/msm_cg.cpp

@@ -72,6 +72,10 @@ MSMCG::~MSMCG()
 
 void MSMCG::compute(int eflag, int vflag)
 {
+  if (scalar_pressure_flag)
+    error->all(FLERR,"Must use 'kspace_modify pressure/scalar no' with "
+      "kspace_style msm/cg");
+
   const double * const q = atom->q;
   const int nlocal = atom->nlocal;
   int i,j,n;

src/KSPACE/msm_cg.h

@@ -56,6 +56,10 @@ Self-explanatory.  Check the input script syntax and compare to the
 documentation for the command.  You can use -echo screen as a
 command-line option when running LAMMPS to see the offending line.
 
+E: Must use 'kspace_modify pressure/scalar no' with kspace_style msm/cg
+
+The kspace scalar pressure option is not compatible with kspace_style msm/cg.
+
 E: Out of range atoms - cannot compute MSM
 
 One or more atoms are attempting to map their charge to a MSM grid point 

src/KSPACE/pair_born_coul_msm.cpp

@@ -39,6 +39,15 @@ PairBornCoulMSM::PairBornCoulMSM(LAMMPS *lmp) : PairBornCoulLong(lmp)
 {
   ewaldflag = pppmflag = 0;
   msmflag = 1;
+  nmax = 0;
+  ftmp = NULL;
+}
+
+/* ---------------------------------------------------------------------- */
+
+PairBornCoulMSM::~PairBornCoulMSM()
+{
+  if (ftmp) memory->destroy(ftmp);
 }
 
 /* ---------------------------------------------------------------------- */
@@ -46,11 +55,31 @@ PairBornCoulMSM::PairBornCoulMSM(LAMMPS *lmp) : PairBornCoulLong(lmp)
 void PairBornCoulMSM::compute(int eflag, int vflag)
 {
   int i,j,ii,jj,inum,jnum,itype,jtype;
-  double qtmp,xtmp,ytmp,ztmp,delx,dely,delz,evdwl,ecoul,fpair;
+  double qtmp,xtmp,ytmp,ztmp,delx,dely,delz,evdwl,ecoul,fpair,fcoul;
   double rsq,r2inv,r6inv,forcecoul,forceborn,factor_coul,factor_lj;
   double egamma,fgamma,prefactor;
   double r,rexp;
   int *ilist,*jlist,*numneigh,**firstneigh;
+  int eflag_old = eflag;
+
+  if (force->kspace->scalar_pressure_flag && vflag) {
+    if (vflag > 2)
+      error->all(FLERR,"Must use 'kspace_modify pressure/scalar no' to "
+        "obtain per-atom virial with kspace_style MSM");
+
+    if (atom->nmax > nmax) {
+      if (ftmp) memory->destroy(ftmp);
+      nmax = atom->nmax;
+      memory->create(ftmp,nmax,3,"pair:ftmp");
+    }
+    memset(&ftmp[0][0],0,nmax*3*sizeof(double));
+
+    // must switch on global energy computation if not already on
+
+    if (eflag == 0 || eflag == 2) {
+      eflag++;
+    }
+  }
 
   evdwl = ecoul = 0.0;
   if (eflag || vflag) ev_setup(eflag,vflag);
@@ -114,15 +143,41 @@ void PairBornCoulMSM::compute(int eflag, int vflag)
             + born3[itype][jtype]*r2inv*r6inv;
         } else forceborn = 0.0;
 
-        fpair = (forcecoul + factor_lj*forceborn) * r2inv;
+        if (!(force->kspace->scalar_pressure_flag && vflag)) {
+          fpair = (forcecoul + factor_lj*forceborn) * r2inv;
 
-        f[i][0] += delx*fpair;
+          f[i][0] += delx*fpair;
-        f[i][1] += dely*fpair;
+          f[i][1] += dely*fpair;
-        f[i][2] += delz*fpair;
+          f[i][2] += delz*fpair;
-        if (newton_pair || j < nlocal) {
+          if (newton_pair || j < nlocal) {
-          f[j][0] -= delx*fpair;
+            f[j][0] -= delx*fpair;
-          f[j][1] -= dely*fpair;
+            f[j][1] -= dely*fpair;
-          f[j][2] -= delz*fpair;
+            f[j][2] -= delz*fpair;
+          }
+        } else {
+          // separate Born and Coulombic forces
+
+          fpair = (factor_lj*forceborn) * r2inv;
+
+          f[i][0] += delx*fpair;
+          f[i][1] += dely*fpair;
+          f[i][2] += delz*fpair;
+          if (newton_pair || j < nlocal) {
+            f[j][0] -= delx*fpair;
+            f[j][1] -= dely*fpair;
+            f[j][2] -= delz*fpair;
+          }
+
+          fcoul = (forcecoul) * r2inv;
+
+          ftmp[i][0] += delx*fcoul;
+          ftmp[i][1] += dely*fcoul;
+          ftmp[i][2] += delz*fcoul;
+          if (newton_pair || j < nlocal) {
+            ftmp[j][0] -= delx*fcoul;
+            ftmp[j][1] -= dely*fcoul;
+            ftmp[j][2] -= delz*fcoul;
+          }
         }
 
         if (eflag) {
@@ -130,7 +185,7 @@ void PairBornCoulMSM::compute(int eflag, int vflag)
             ecoul = prefactor*egamma;
             if (factor_coul < 1.0) ecoul -= (1.0-factor_coul)*prefactor;
           } else ecoul = 0.0;
-          if (rsq < cut_ljsq[itype][jtype]) {
+          if (eflag_old && rsq < cut_ljsq[itype][jtype]) {
             evdwl = a[itype][jtype]*rexp - c[itype][jtype]*r6inv
               + d[itype][jtype]*r6inv*r2inv - offset[itype][jtype];
             evdwl *= factor_lj;
@@ -144,6 +199,15 @@ void PairBornCoulMSM::compute(int eflag, int vflag)
   }
 
   if (vflag_fdotr) virial_fdotr_compute();
+
+  if (force->kspace->scalar_pressure_flag && vflag) {
+    for (i = 0; i < 3; i++) virial[i] += force->pair->eng_coul/3.0;
+    for (int i = 0; i < nmax; i++) {
+      f[i][0] += ftmp[i][0];
+      f[i][1] += ftmp[i][1];  
+      f[i][2] += ftmp[i][2];  
+    }
+  }
 }
 
 /* ---------------------------------------------------------------------- */

src/KSPACE/pair_born_coul_msm.h

@@ -27,10 +27,13 @@ namespace LAMMPS_NS {
 class PairBornCoulMSM : public PairBornCoulLong {
  public:
   PairBornCoulMSM(class LAMMPS *);
-  virtual ~PairBornCoulMSM(){};
+  virtual ~PairBornCoulMSM();
   virtual void compute(int, int);
   virtual double single(int, int, int, int, double, double, double, double &);
   virtual void *extract(const char *, int &);
+ protected:
+  int nmax;
+  double **ftmp;
 
 };
 
@@ -65,4 +68,8 @@ E: Pair style is incompatible with KSpace style
 If a pair style with a long-range Coulombic component is selected,
 then a kspace style must also be used.
 
+E: Must use 'kspace_modify pressure/scalar no' to obtain per-atom virial with kspace_style MSM
+
+The kspace scalar pressure option cannot be used to obtain per-atom virial.
+
 */

src/KSPACE/pair_buck_coul_msm.cpp

@@ -36,6 +36,15 @@ PairBuckCoulMSM::PairBuckCoulMSM(LAMMPS *lmp) : PairBuckCoulLong(lmp)
 {
   ewaldflag = pppmflag = 0;
   msmflag = 1;
+  nmax = 0;
+  ftmp = NULL;
+}
+
+/* ---------------------------------------------------------------------- */
+
+PairBuckCoulMSM::~PairBuckCoulMSM()
+{
+  if (ftmp) memory->destroy(ftmp);
 }
 
 /* ---------------------------------------------------------------------- */
@@ -43,11 +52,31 @@ PairBuckCoulMSM::PairBuckCoulMSM(LAMMPS *lmp) : PairBuckCoulLong(lmp)
 void PairBuckCoulMSM::compute(int eflag, int vflag)
 {
   int i,j,ii,jj,inum,jnum,itype,jtype;
-  double qtmp,xtmp,ytmp,ztmp,delx,dely,delz,evdwl,ecoul,fpair;
+  double qtmp,xtmp,ytmp,ztmp,delx,dely,delz,evdwl,ecoul,fpair,fcoul;
   double rsq,r2inv,r6inv,forcecoul,forcebuck,factor_coul,factor_lj;
   double egamma,fgamma,prefactor;
   double r,rexp;
   int *ilist,*jlist,*numneigh,**firstneigh;
+  int eflag_old = eflag;
+
+  if (force->kspace->scalar_pressure_flag && vflag) {
+    if (vflag > 2)
+      error->all(FLERR,"Must use 'kspace_modify pressure/scalar no' "
+        "to obtain per-atom virial with kspace_style MSM");
+
+    if (atom->nmax > nmax) {
+      if (ftmp) memory->destroy(ftmp);
+      nmax = atom->nmax;
+      memory->create(ftmp,nmax,3,"pair:ftmp");
+    }
+    memset(&ftmp[0][0],0,nmax*3*sizeof(double));
+
+    // must switch on global energy computation if not already on
+
+    if (eflag == 0 || eflag == 2) {
+      eflag++;
+    }
+  }
 
   evdwl = ecoul = 0.0;
   if (eflag || vflag) ev_setup(eflag,vflag);
@@ -110,15 +139,41 @@ void PairBuckCoulMSM::compute(int eflag, int vflag)
           forcebuck = buck1[itype][jtype]*r*rexp - buck2[itype][jtype]*r6inv;
         } else forcebuck = 0.0;
 
-        fpair = (forcecoul + factor_lj*forcebuck) * r2inv;
+        if (!(force->kspace->scalar_pressure_flag && vflag)) {
+          fpair = (forcecoul + factor_lj*forcebuck) * r2inv;
 
-        f[i][0] += delx*fpair;
+          f[i][0] += delx*fpair;
-        f[i][1] += dely*fpair;
+          f[i][1] += dely*fpair;
-        f[i][2] += delz*fpair;
+          f[i][2] += delz*fpair;
-        if (newton_pair || j < nlocal) {
+          if (newton_pair || j < nlocal) {
-          f[j][0] -= delx*fpair;
+            f[j][0] -= delx*fpair;
-          f[j][1] -= dely*fpair;
+            f[j][1] -= dely*fpair;
-          f[j][2] -= delz*fpair;
+            f[j][2] -= delz*fpair;
+          }
+        } else {
+          // separate Buck and Coulombic forces
+
+          fpair = (factor_lj*forcebuck) * r2inv;
+
+          f[i][0] += delx*fpair;
+          f[i][1] += dely*fpair;
+          f[i][2] += delz*fpair;
+          if (newton_pair || j < nlocal) {
+            f[j][0] -= delx*fpair;
+            f[j][1] -= dely*fpair;
+            f[j][2] -= delz*fpair;
+          }
+
+          fcoul = (forcecoul) * r2inv;
+
+          ftmp[i][0] += delx*fcoul;
+          ftmp[i][1] += dely*fcoul;
+          ftmp[i][2] += delz*fcoul;
+          if (newton_pair || j < nlocal) {
+            ftmp[j][0] -= delx*fcoul;
+            ftmp[j][1] -= dely*fcoul;
+            ftmp[j][2] -= delz*fcoul;
+          }
         }
 
         if (eflag) {
@@ -126,7 +181,7 @@ void PairBuckCoulMSM::compute(int eflag, int vflag)
             ecoul = prefactor*egamma;
             if (factor_coul < 1.0) ecoul -= (1.0-factor_coul)*prefactor;
           } else ecoul = 0.0;
-          if (rsq < cut_ljsq[itype][jtype]) {
+          if (eflag_old && rsq < cut_ljsq[itype][jtype]) {
             evdwl = a[itype][jtype]*rexp - c[itype][jtype]*r6inv -
               offset[itype][jtype];
             evdwl *= factor_lj;
@@ -140,6 +195,15 @@ void PairBuckCoulMSM::compute(int eflag, int vflag)
   }
 
   if (vflag_fdotr) virial_fdotr_compute();
+
+  if (force->kspace->scalar_pressure_flag && vflag) {
+    for (i = 0; i < 3; i++) virial[i] += force->pair->eng_coul/3.0;
+    for (int i = 0; i < nmax; i++) {
+      f[i][0] += ftmp[i][0];
+      f[i][1] += ftmp[i][1];  
+      f[i][2] += ftmp[i][2];  
+    }
+  }
 }
 
 /* ---------------------------------------------------------------------- */

src/KSPACE/pair_buck_coul_msm.h

@@ -27,11 +27,13 @@ namespace LAMMPS_NS {
 class PairBuckCoulMSM : public PairBuckCoulLong {
  public:
   PairBuckCoulMSM(class LAMMPS *);
-  virtual ~PairBuckCoulMSM(){};
+  virtual ~PairBuckCoulMSM();
   virtual void compute(int, int);
   virtual double single(int, int, int, int, double, double, double, double &);
   virtual void *extract(const char *, int &);
-  
+ protected:
+  int nmax;
+  double **ftmp;
 };
 
 }
@@ -65,4 +67,8 @@ E: Pair style is incompatible with KSpace style
 If a pair style with a long-range Coulombic component is selected,
 then a kspace style must also be used.
 
+E: Must use 'kspace_modify pressure/scalar no' to obtain per-atom virial with kspace_style MSM
+
+The kspace scalar pressure option cannot be used to obtain per-atom virial.
+
 */

src/KSPACE/pair_coul_msm.cpp

@@ -53,7 +53,19 @@ void PairCoulMSM::compute(int eflag, int vflag)
   double egamma,fgamma,prefactor;
   int *ilist,*jlist,*numneigh,**firstneigh;
   double rsq;
-  
+
+  if (force->kspace->scalar_pressure_flag && vflag) {
+    if (vflag > 2)
+      error->all(FLERR,"Must use 'kspace_modify pressure/scalar no' "
+        "to obtain per-atom virial with kspace_style MSM");
+
+    // must switch on global energy computation if not already on
+
+    if (eflag == 0 || eflag == 2) {
+      eflag++;
+    }
+  }
+
   ecoul = 0.0;
   if (eflag || vflag) ev_setup(eflag,vflag);
   else evflag = vflag_fdotr = 0;
@@ -140,13 +152,19 @@ void PairCoulMSM::compute(int eflag, int vflag)
           if (factor_coul < 1.0) ecoul -= (1.0-factor_coul)*prefactor;
         }
 
+        if (force->kspace->scalar_pressure_flag)
+          fpair = 0.0;
+
         if (evflag) ev_tally(i,j,nlocal,newton_pair,
                              0.0,ecoul,fpair,delx,dely,delz);
       }
     }
   }
 
-  if (vflag_fdotr) virial_fdotr_compute();
+  if (vflag_fdotr && !force->kspace->scalar_pressure_flag)
+    virial_fdotr_compute();
+  if (force->kspace->scalar_pressure_flag && vflag)
+    for (i = 0; i < 3; i++) virial[i] += force->pair->eng_coul/3.0;
 }
 
 /* ---------------------------------------------------------------------- */

src/KSPACE/pair_coul_msm.h

@@ -64,4 +64,8 @@ E: Pair style is incompatible with KSpace style
 If a pair style with a long-range Coulombic component is selected,
 then a kspace style must also be used.
 
+E: Must use 'kspace_modify pressure/scalar no' to obtain per-atom virial with kspace_style MSM
+
+The kspace scalar pressure option cannot be used to obtain per-atom virial.
+
 */

src/KSPACE/pair_lj_charmm_coul_msm.cpp

@@ -42,6 +42,15 @@ PairLJCharmmCoulMSM::PairLJCharmmCoulMSM(LAMMPS *lmp) :
 {
   ewaldflag = pppmflag = 0;
   msmflag = 1;
+  nmax = 0;
+  ftmp = NULL;
+}
+
+/* ---------------------------------------------------------------------- */
+
+PairLJCharmmCoulMSM::~PairLJCharmmCoulMSM()
+{
+  if (ftmp) memory->destroy(ftmp);
 }
 
 /* ---------------------------------------------------------------------- */
@@ -49,13 +58,33 @@ PairLJCharmmCoulMSM::PairLJCharmmCoulMSM(LAMMPS *lmp) :
 void PairLJCharmmCoulMSM::compute(int eflag, int vflag)
 {
   int i,j,ii,jj,inum,jnum,itype,jtype,itable;
-  double qtmp,xtmp,ytmp,ztmp,delx,dely,delz,evdwl,ecoul,fpair;
+  double qtmp,xtmp,ytmp,ztmp,delx,dely,delz,evdwl,ecoul,fpair,fcoul;
   double fraction,table;
   double r,r2inv,r6inv,forcecoul,forcelj,factor_coul,factor_lj;
   double egamma,fgamma,prefactor;
   double philj,switch1,switch2;
   int *ilist,*jlist,*numneigh,**firstneigh;
   double rsq;
+  int eflag_old = eflag;
+
+  if (force->kspace->scalar_pressure_flag && vflag) {
+    if (vflag > 2)
+      error->all(FLERR,"Must use 'kspace_modify pressure/scalar no' "
+        "to obtain per-atom virial with kspace_style MSM");
+
+    if (atom->nmax > nmax) {
+      if (ftmp) memory->destroy(ftmp);
+      nmax = atom->nmax;
+      memory->create(ftmp,nmax,3,"pair:ftmp");
+    }
+    memset(&ftmp[0][0],0,nmax*3*sizeof(double));
+
+    // must switch on global energy computation if not already on
+
+    if (eflag == 0 || eflag == 2) {
+      eflag++;
+    }
+  }
 
   evdwl = ecoul = 0.0;
   if (eflag || vflag) ev_setup(eflag,vflag);
@@ -140,15 +169,41 @@ void PairLJCharmmCoulMSM::compute(int eflag, int vflag)
           }
         } else forcelj = 0.0;
 
-        fpair = (forcecoul + factor_lj*forcelj) * r2inv;
+        if (!(force->kspace->scalar_pressure_flag && vflag)) {
+          fpair = (forcecoul + factor_lj*forcelj) * r2inv;
 
-        f[i][0] += delx*fpair;
+          f[i][0] += delx*fpair;
-        f[i][1] += dely*fpair;
+          f[i][1] += dely*fpair;
-        f[i][2] += delz*fpair;
+          f[i][2] += delz*fpair;
-        if (newton_pair || j < nlocal) {
+          if (newton_pair || j < nlocal) {
-          f[j][0] -= delx*fpair;
+            f[j][0] -= delx*fpair;
-          f[j][1] -= dely*fpair;
+            f[j][1] -= dely*fpair;
-          f[j][2] -= delz*fpair;
+            f[j][2] -= delz*fpair;
+          }
+        } else {
+          // separate LJ and Coulombic forces
+
+          fpair = (factor_lj*forcelj) * r2inv;
+
+          f[i][0] += delx*fpair;
+          f[i][1] += dely*fpair;
+          f[i][2] += delz*fpair;
+          if (newton_pair || j < nlocal) {
+            f[j][0] -= delx*fpair;
+            f[j][1] -= dely*fpair;
+            f[j][2] -= delz*fpair;
+          }
+
+          fcoul = (forcecoul) * r2inv;
+
+          ftmp[i][0] += delx*fcoul;
+          ftmp[i][1] += dely*fcoul;
+          ftmp[i][2] += delz*fcoul;
+          if (newton_pair || j < nlocal) {
+            ftmp[j][0] -= delx*fcoul;
+            ftmp[j][1] -= dely*fcoul;
+            ftmp[j][2] -= delz*fcoul;
+          }
         }
 
         if (eflag) {
@@ -162,7 +217,7 @@ void PairLJCharmmCoulMSM::compute(int eflag, int vflag)
             if (factor_coul < 1.0) ecoul -= (1.0-factor_coul)*prefactor;
           } else ecoul = 0.0;
 
-          if (rsq < cut_ljsq) {
+          if (eflag_old && rsq < cut_ljsq) {
             evdwl = r6inv*(lj3[itype][jtype]*r6inv-lj4[itype][jtype]);
             if (rsq > cut_lj_innersq) {
               switch1 = (cut_ljsq-rsq) * (cut_ljsq-rsq) *
@@ -180,6 +235,15 @@ void PairLJCharmmCoulMSM::compute(int eflag, int vflag)
   }
 
   if (vflag_fdotr) virial_fdotr_compute();
+
+  if (force->kspace->scalar_pressure_flag && vflag) {
+    for (i = 0; i < 3; i++) virial[i] += force->pair->eng_coul/3.0;
+    for (int i = 0; i < nmax; i++) {
+      f[i][0] += ftmp[i][0];
+      f[i][1] += ftmp[i][1];  
+      f[i][2] += ftmp[i][2];  
+    }
+  }
 }
 
 /* ---------------------------------------------------------------------- */
@@ -196,6 +260,10 @@ void PairLJCharmmCoulMSM::compute_outer(int eflag, int vflag)
   int *ilist,*jlist,*numneigh,**firstneigh;
   double rsq;
 
+  if (force->kspace->scalar_pressure_flag)
+   error->all(FLERR,"Must use 'kspace_modify pressure/scalar no' "
+     "for rRESPA with kspace_style MSM");
+
   evdwl = ecoul = 0.0;
   if (eflag || vflag) ev_setup(eflag,vflag);
   else evflag = 0;

src/KSPACE/pair_lj_charmm_coul_msm.h

@@ -27,11 +27,14 @@ namespace LAMMPS_NS {
 class PairLJCharmmCoulMSM : public PairLJCharmmCoulLong {
  public:
   PairLJCharmmCoulMSM(class LAMMPS *);
-  virtual ~PairLJCharmmCoulMSM(){};
+  virtual ~PairLJCharmmCoulMSM();
   virtual void compute(int, int);
   virtual double single(int, int, int, int, double, double, double, double &);
   virtual void compute_outer(int, int);
   virtual void *extract(const char *, int &);
+ protected:
+  int nmax;
+  double **ftmp;
 };
 
 }
@@ -59,6 +62,15 @@ E: Pair inner cutoff >= Pair outer cutoff
 
 The specified cutoffs for the pair style are inconsistent.
 
+E: Must use 'kspace_modify pressure/scalar no' to obtain per-atom virial
+with kspace_style MSM
+
+The kspace scalar pressure option cannot be used to obtain per-atom virial.
+
+E: Must use 'kspace_modify pressure/scalar no' for rRESPA with kspace_style MSM
+
+The kspace scalar pressure option cannot (yet) be used with rRESPA.
+
 E: Pair cutoff < Respa interior cutoff
 
 One or more pairwise cutoffs are too short to use with the specified

src/KSPACE/pair_lj_cut_coul_msm.cpp

@@ -43,6 +43,15 @@ PairLJCutCoulMSM::PairLJCutCoulMSM(LAMMPS *lmp) : PairLJCutCoulLong(lmp)
 {
   ewaldflag = pppmflag = 0;
   msmflag = 1;
+  nmax = 0;
+  ftmp = NULL;
+}
+
+/* ---------------------------------------------------------------------- */
+
+PairLJCutCoulMSM::~PairLJCutCoulMSM()
+{
+  if (ftmp) memory->destroy(ftmp);
 }
 
 /* ---------------------------------------------------------------------- */
@@ -50,12 +59,32 @@ PairLJCutCoulMSM::PairLJCutCoulMSM(LAMMPS *lmp) : PairLJCutCoulLong(lmp)
 void PairLJCutCoulMSM::compute(int eflag, int vflag)
 {
   int i,ii,j,jj,inum,jnum,itype,jtype,itable;
-  double qtmp,xtmp,ytmp,ztmp,delx,dely,delz,evdwl,ecoul,fpair;
+  double qtmp,xtmp,ytmp,ztmp,delx,dely,delz,evdwl,ecoul,fpair,fcoul;
   double fraction,table;
   double r,r2inv,r6inv,forcecoul,forcelj,factor_coul,factor_lj;
   double egamma,fgamma,prefactor;
   int *ilist,*jlist,*numneigh,**firstneigh;
   double rsq;
+  int eflag_old = eflag;
+
+  if (force->kspace->scalar_pressure_flag && vflag) {
+    if (vflag > 2)
+      error->all(FLERR,"Must use 'kspace_modify pressure/scalar no' "
+        "to obtain per-atom virial with kspace_style MSM");
+
+    if (atom->nmax > nmax) {
+      if (ftmp) memory->destroy(ftmp);
+      nmax = atom->nmax;
+      memory->create(ftmp,nmax,3,"pair:ftmp");
+    }
+    memset(&ftmp[0][0],0,nmax*3*sizeof(double));
+
+    // must switch on global energy computation if not already on
+
+    if (eflag == 0 || eflag == 2) {
+      eflag++;
+    }
+  }
 
   evdwl = ecoul = 0.0;
   if (eflag || vflag) ev_setup(eflag,vflag);
@@ -132,15 +161,41 @@ void PairLJCutCoulMSM::compute(int eflag, int vflag)
           forcelj = r6inv * (lj1[itype][jtype]*r6inv - lj2[itype][jtype]);
         } else forcelj = 0.0;
 
-        fpair = (forcecoul + factor_lj*forcelj) * r2inv;
+        if (!(force->kspace->scalar_pressure_flag && vflag)) {
+          fpair = (forcecoul + factor_lj*forcelj) * r2inv;
 
-        f[i][0] += delx*fpair;
+          f[i][0] += delx*fpair;
-        f[i][1] += dely*fpair;
+          f[i][1] += dely*fpair;
-        f[i][2] += delz*fpair;
+          f[i][2] += delz*fpair;
-        if (newton_pair || j < nlocal) {
+          if (newton_pair || j < nlocal) {
-          f[j][0] -= delx*fpair;
+            f[j][0] -= delx*fpair;
-          f[j][1] -= dely*fpair;
+            f[j][1] -= dely*fpair;
-          f[j][2] -= delz*fpair;
+            f[j][2] -= delz*fpair;
+          }
+        } else {
+          // separate LJ and Coulombic forces
+
+          fpair = (factor_lj*forcelj) * r2inv;
+
+          f[i][0] += delx*fpair;
+          f[i][1] += dely*fpair;
+          f[i][2] += delz*fpair;
+          if (newton_pair || j < nlocal) {
+            f[j][0] -= delx*fpair;
+            f[j][1] -= dely*fpair;
+            f[j][2] -= delz*fpair;
+          }
+
+          fcoul = (forcecoul) * r2inv;
+
+          ftmp[i][0] += delx*fcoul;
+          ftmp[i][1] += dely*fcoul;
+          ftmp[i][2] += delz*fcoul;
+          if (newton_pair || j < nlocal) {
+            ftmp[j][0] -= delx*fcoul;
+            ftmp[j][1] -= dely*fcoul;
+            ftmp[j][2] -= delz*fcoul;
+          }
         }
 
         if (eflag) {
@@ -154,7 +209,7 @@ void PairLJCutCoulMSM::compute(int eflag, int vflag)
             if (factor_coul < 1.0) ecoul -= (1.0-factor_coul)*prefactor;
           } else ecoul = 0.0;
 
-          if (rsq < cut_ljsq[itype][jtype]) {
+          if (eflag_old && rsq < cut_ljsq[itype][jtype]) {
             evdwl = r6inv*(lj3[itype][jtype]*r6inv-lj4[itype][jtype]) -
               offset[itype][jtype];
             evdwl *= factor_lj;
@@ -168,6 +223,15 @@ void PairLJCutCoulMSM::compute(int eflag, int vflag)
   }
 
   if (vflag_fdotr) virial_fdotr_compute();
+
+  if (force->kspace->scalar_pressure_flag && vflag) {
+    for (i = 0; i < 3; i++) virial[i] += force->pair->eng_coul/3.0;
+    for (int i = 0; i < nmax; i++) {
+      f[i][0] += ftmp[i][0];
+      f[i][1] += ftmp[i][1];  
+      f[i][2] += ftmp[i][2];  
+    }
+  }
 }
 
 /* ---------------------------------------------------------------------- */
@@ -183,6 +247,10 @@ void PairLJCutCoulMSM::compute_outer(int eflag, int vflag)
   int *ilist,*jlist,*numneigh,**firstneigh;
   double rsq;
 
+  if (force->kspace->scalar_pressure_flag)
+   error->all(FLERR,"Must use 'kspace_modify pressure/scalar no' "
+     "for rRESPA with kspace_style MSM");
+
   evdwl = ecoul = 0.0;
   if (eflag || vflag) ev_setup(eflag,vflag);
   else evflag = 0;

src/KSPACE/pair_lj_cut_coul_msm.h

@@ -27,11 +27,14 @@ namespace LAMMPS_NS {
 class PairLJCutCoulMSM : public PairLJCutCoulLong {
  public:
   PairLJCutCoulMSM(class LAMMPS *);
-  virtual ~PairLJCutCoulMSM(){};
+  virtual ~PairLJCutCoulMSM();
   virtual void compute(int, int);
   virtual double single(int, int, int, int, double, double, double, double &);
   virtual void compute_outer(int, int);
   virtual void *extract(const char *, int &);
+ protected:
+  int nmax;
+  double **ftmp;
 };
 
 }
@@ -60,6 +63,14 @@ E: Pair style is incompatible with KSpace style
 If a pair style with a long-range Coulombic component is selected,
 then a kspace style must also be used.
 
+E: Must use 'kspace_modify pressure/scalar no' to obtain per-atom virial with kspace_style MSM
+
+The kspace scalar pressure option cannot be used to obtain per-atom virial.
+
+E: Must use 'kspace_modify pressure/scalar no' for rRESPA with kspace_style MSM
+
+The kspace scalar pressure option cannot (yet) be used with rRESPA.
+
 E: Pair cutoff < Respa interior cutoff
 
 One or more pairwise cutoffs are too short to use with the specified

src/USER-CG-CMM/pair_lj_sdk_coul_msm.cpp

@@ -54,6 +54,9 @@ PairLJSDKCoulMSM::PairLJSDKCoulMSM(LAMMPS *lmp) : PairLJSDKCoulLong(lmp)
 
 void PairLJSDKCoulMSM::compute(int eflag, int vflag)
 {
+  if (force->kspace->scalar_pressure_flag)
+    error->all(FLERR,"Must use 'kspace_modify pressure/scalar no' with Pair style");
+
   if (eflag || vflag) {
     ev_setup(eflag,vflag);
   } else evflag = vflag_fdotr = 0;

src/USER-CG-CMM/pair_lj_sdk_coul_msm.h

@@ -46,3 +46,12 @@ private:
 
 #endif
 #endif
+
+/* ERROR/WARNING messages:
+
+E: Must use 'kspace_modify pressure/scalar no' with Pair style
+
+The kspace scalar pressure option is not (yet) compatible with at least one of
+the defined Pair styles.
+
+*/

src/USER-OMP/msm_cg_omp.cpp

@@ -73,6 +73,10 @@ MSMCGOMP::~MSMCGOMP()
 
 void MSMCGOMP::compute(int eflag, int vflag)
 {
+  if (scalar_pressure_flag)
+    error->all(FLERR,"Must use 'kspace_modify pressure/scalar no' "
+      "with kspace_style msm/cg/omp");
+
   const double * const q = atom->q;
   const int nlocal = atom->nlocal;
   int i,j,n;

src/USER-OMP/msm_cg_omp.h

@@ -56,6 +56,10 @@ Self-explanatory.  Check the input script syntax and compare to the
 documentation for the command.  You can use -echo screen as a
 command-line option when running LAMMPS to see the offending line.
 
+E: Must use 'kspace_modify pressure/scalar no' with kspace_style msm/cg/omp
+
+The kspace scalar pressure option is not compatible with kspace_style msm/cg/omp.
+
 E: Cannot (yet) use MSM with triclinic box
 
 This feature is not yet supported.

src/USER-OMP/msm_omp.cpp

@@ -50,6 +50,9 @@ MSMOMP::MSMOMP(LAMMPS *lmp, int narg, char **arg) :
 
 void MSMOMP::compute(int eflag, int vflag)
 {
+  if (scalar_pressure_flag)
+    error->all(FLERR,"Must use 'kspace_modify pressure/scalar no' "
+      "with kspace_style msm/omp");
 
   MSM::compute(eflag,vflag);
 

src/USER-OMP/msm_omp.h

@@ -44,3 +44,11 @@ namespace LAMMPS_NS {
 
 #endif
 #endif
+
+/* ERROR/WARNING messages:
+
+E: Must use 'kspace_modify pressure/scalar no' with kspace_style msm/omp
+
+The kspace scalar pressure option is not compatible with kspace_style msm/omp.
+
+*/

src/USER-OMP/pair_born_coul_msm_omp.cpp

@@ -37,6 +37,10 @@ PairBornCoulMSMOMP::PairBornCoulMSMOMP(LAMMPS *lmp) :
 
 void PairBornCoulMSMOMP::compute(int eflag, int vflag)
 {
+  if (force->kspace->scalar_pressure_flag)
+    error->all(FLERR,"Must use 'kspace_modify pressure/scalar no' "
+      "with OMP MSM Pair styles");
+
   if (eflag || vflag) {
     ev_setup(eflag,vflag);
   } else evflag = vflag_fdotr = 0;

src/USER-OMP/pair_born_coul_msm_omp.h

@@ -46,3 +46,11 @@ class PairBornCoulMSMOMP : public PairBornCoulMSM, public ThrOMP {
 
 #endif
 #endif
+
+/* ERROR/WARNING messages:
+
+E: Must use 'kspace_modify pressure/scalar no' with OMP MSM Pair styles
+
+The kspace scalar pressure option is not (yet) compatible with OMP MSM Pair styles.
+
+*/

src/USER-OMP/pair_buck_coul_msm_omp.cpp

@@ -37,6 +37,10 @@ PairBuckCoulMSMOMP::PairBuckCoulMSMOMP(LAMMPS *lmp) :
 
 void PairBuckCoulMSMOMP::compute(int eflag, int vflag)
 {
+  if (force->kspace->scalar_pressure_flag)
+    error->all(FLERR,"Must use 'kspace_modify pressure/scalar no' "
+      "with OMP MSM Pair styles");
+
   if (eflag || vflag) {
     ev_setup(eflag,vflag);
   } else evflag = vflag_fdotr = 0;

src/USER-OMP/pair_buck_coul_msm_omp.h

@@ -46,3 +46,11 @@ class PairBuckCoulMSMOMP : public PairBuckCoulMSM, public ThrOMP {
 
 #endif
 #endif
+
+/* ERROR/WARNING messages:
+
+E: Must use 'kspace_modify pressure/scalar no' with OMP MSM Pair styles
+
+The kspace scalar pressure option is not (yet) compatible with OMP MSM Pair styles.
+
+*/

src/USER-OMP/pair_coul_msm_omp.cpp

@@ -38,6 +38,10 @@ PairCoulMSMOMP::PairCoulMSMOMP(LAMMPS *lmp) :
 
 void PairCoulMSMOMP::compute(int eflag, int vflag)
 {
+  if (force->kspace->scalar_pressure_flag)
+    error->all(FLERR,"Must use 'kspace_modify pressure/scalar no' with "
+      "OMP MSM Pair styles");
+
   if (eflag || vflag) {
     ev_setup(eflag,vflag);
   } else evflag = vflag_fdotr = 0;

src/USER-OMP/pair_coul_msm_omp.h

@@ -46,3 +46,11 @@ class PairCoulMSMOMP : public PairCoulMSM, public ThrOMP {
 
 #endif
 #endif
+
+/* ERROR/WARNING messages:
+
+E: Must use 'kspace_modify pressure/scalar no' with OMP MSM Pair styles
+
+The kspace scalar pressure option is not (yet) compatible with OMP MSM Pair styles.
+
+*/

src/USER-OMP/pair_lj_charmm_coul_msm_omp.cpp

@@ -38,6 +38,10 @@ PairLJCharmmCoulMSMOMP::PairLJCharmmCoulMSMOMP(LAMMPS *lmp) :
 
 void PairLJCharmmCoulMSMOMP::compute(int eflag, int vflag)
 {
+  if (force->kspace->scalar_pressure_flag)
+    error->all(FLERR,"Must use 'kspace_modify pressure/scalar no' "
+      "with OMP MSM Pair styles");
+
   if (eflag || vflag) {
     ev_setup(eflag,vflag);
   } else evflag = vflag_fdotr = 0;

src/USER-OMP/pair_lj_charmm_coul_msm_omp.h

@@ -46,3 +46,11 @@ class PairLJCharmmCoulMSMOMP : public PairLJCharmmCoulMSM, public ThrOMP {
 
 #endif
 #endif
+
+/* ERROR/WARNING messages:
+
+E: Must use 'kspace_modify pressure/scalar no' with OMP MSM Pair styles
+
+The kspace scalar pressure option is not (yet) compatible with OMP MSM Pair styles.
+
+*/

src/USER-OMP/pair_lj_cut_coul_msm_omp.cpp

@@ -38,6 +38,10 @@ PairLJCutCoulMSMOMP::PairLJCutCoulMSMOMP(LAMMPS *lmp) :
 
 void PairLJCutCoulMSMOMP::compute(int eflag, int vflag)
 {
+  if (force->kspace->scalar_pressure_flag)
+    error->all(FLERR,"Must use 'kspace_modify pressure/scalar no' "
+      "with OMP MSM Pair styles");
+
   if (eflag || vflag) {
     ev_setup(eflag,vflag);
   } else evflag = vflag_fdotr = 0;

src/USER-OMP/pair_lj_cut_coul_msm_omp.h

@@ -46,3 +46,11 @@ class PairLJCutCoulMSMOMP : public PairLJCutCoulMSM, public ThrOMP {
 
 #endif
 #endif
+
+/* ERROR/WARNING messages:
+
+E: Must use 'kspace_modify pressure/scalar no' with OMP MSM Pair styles
+
+The kspace scalar pressure option is not (yet) compatible with OMP MSM Pair styles.
+
+*/

src/USER-OMP/pair_lj_sdk_coul_msm_omp.cpp

@@ -40,6 +40,10 @@ PairLJSDKCoulMSMOMP::PairLJSDKCoulMSMOMP(LAMMPS *lmp) :
 
 void PairLJSDKCoulMSMOMP::compute(int eflag, int vflag)
 {
+  if (force->kspace->scalar_pressure_flag)
+    error->all(FLERR,"Must use 'kspace_modify pressure/scalar no' "
+      "with OMP MSM Pair styles");
+
   if (eflag || vflag) {
     ev_setup(eflag,vflag);
   } else evflag = vflag_fdotr = 0;

src/USER-OMP/pair_lj_sdk_coul_msm_omp.h

@@ -47,3 +47,11 @@ class PairLJSDKCoulMSMOMP : public PairLJSDKCoulMSM, public ThrOMP {
 
 #endif
 #endif
+
+/* ERROR/WARNING messages:
+
+E: Must use 'kspace_modify pressure/scalar no' with OMP MSM Pair styles
+
+The kspace scalar pressure option is not (yet) compatible with OMP MSM Pair styles.
+
+*/

src/compute_pressure.cpp

@@ -59,8 +59,8 @@ ComputePressure::ComputePressure(LAMMPS *lmp, int narg, char **arg) :
     if (icompute < 0)
       error->all(FLERR,"Could not find compute pressure temperature ID");
     if (modify->compute[icompute]->tempflag == 0)
-      error->all(FLERR,
+      error->all(FLERR,"Compute pressure temperature ID does not "
-		 "Compute pressure temperature ID does not compute temperature");
+                 "compute temperature");
   }
 
   // process optional args
@@ -221,6 +221,10 @@ void ComputePressure::compute_vector()
   if (update->vflag_global != invoked_vector)
     error->all(FLERR,"Virial was not tallied on needed timestep");
 
+  if (force->kspace && kspace_virial && force->kspace->scalar_pressure_flag)
+    error->all(FLERR,"Kspace_modify pressure/scalar no required "
+               "for components of pressure tensor with kspace_style msm");
+
   // invoke temperature if it hasn't been already
 
   double *ke_tensor;

src/compute_pressure.h

@@ -74,6 +74,11 @@ E: Compute pressure temperature ID does not compute temperature
 The compute ID assigned to a pressure computation must compute
 temperature.
 
+E: Must use 'kspace_modify pressure/scalar no' to get individual
+components of pressure tensor with kspace_style MSM
+
+Self-explanatory.
+
 E: Virial was not tallied on needed timestep
 
 You are using a thermo keyword that requires potentials to

src/kspace.cpp

@@ -65,6 +65,7 @@ KSpace::KSpace(LAMMPS *lmp, int narg, char **arg) : Pointers(lmp)
   slab_volfactor = 1;
   suffix_flag = Suffix::NONE;
   adjust_cutoff_flag = 1;
+  scalar_pressure_flag = 0;
 
   accuracy_absolute = -1.0;
   accuracy_real_6 = -1.0;
@@ -490,6 +491,12 @@ void KSpace::modify_params(int narg, char **arg)
       if (splittol >= 1.0) 
         error->all(FLERR,"Kspace_modify eigtol must be smaller than one");
       iarg += 2;
+    } else if (strcmp(arg[iarg],"pressure/scalar") == 0) {
+      if (iarg+2 > narg) error->all(FLERR,"Illegal kspace_modify command");
+      if (strcmp(arg[iarg+1],"yes") == 0) scalar_pressure_flag = 1;
+      else if (strcmp(arg[iarg+1],"no") == 0) scalar_pressure_flag = 0;
+      else error->all(FLERR,"Illegal kspace_modify command");
+      iarg += 2;
     } else error->all(FLERR,"Illegal kspace_modify command");
   }
 }

src/kspace.h

@@ -48,6 +48,7 @@ class KSpace : protected Pointers {
   int neighrequest_flag;         // used to avoid obsolete construction of neighbor lists
   int mixflag;                   // 1 if geometric mixing rules are enforced for LJ coefficients
   int slabflag;
+  int scalar_pressure_flag;      // 1 if using MSM fast scalar pressure
   double slab_volfactor;