git-svn-id: svn://svn.icms.temple.edu/lammps-ro/trunk@13112 f3b2605a-c512-4ea7-a41b-209d697bcdaa

src/KSPACE/pppm_disp.cpp

@@ -287,6 +287,17 @@ void PPPMDisp::init()
     error->warning(FLERR, str);
   }
 
+  // show error message if pppm/disp is not used correctly
+
+  if (function[1] || function[2] || function[3]) {
+    if (!gridflag_6 && !gewaldflag_6 && accuracy_real_6 < 0
+        && accuracy_kspace_6 < 0 && !auto_disp_flag) {
+      error->all(FLERR, "PPPMDisp used but no parameters set, "
+              "for further information please see the pppm/disp "
+              "documentation");
+    }
+  }
+
   // compute qsum & qsqsum, if function[0] is set, warn if not charge-neutral
 
   scale = 1.0;

src/KSPACE/pppm_disp.h

@@ -493,6 +493,10 @@ E: Epsilon or sigma reference not set by pair style in PPPMDisp
 
 Self-explanatory.
 
+E: PPPMDisp used but no parameters set, for further information please see the pppm/disp documentation
+
+An efficient and accurate usage of the pppm/disp requires settings via the kspace_modify command. Please see the pppm/disp documentation for further instructions.
+
 E: KSpace accuracy too large to estimate G vector
 
 Reduce the accuracy request or specify gwald explicitly

src/kspace.cpp

@@ -61,6 +61,7 @@ KSpace::KSpace(LAMMPS *lmp, int narg, char **arg) : Pointers(lmp)
   order_6 = 5;
   gridflag_6 = 0;
   gewaldflag_6 = 0;
+  auto_disp_flag = 0;
 
   slabflag = 0;
   differentiation_flag = 0;
@@ -556,6 +557,12 @@ void KSpace::modify_params(int narg, char **arg)
       else if (strcmp(arg[iarg+1],"no") == 0) scalar_pressure_flag = 0;
       else error->all(FLERR,"Illegal kspace_modify command");
       iarg += 2;
+    } else if (strcmp(arg[iarg],"disp/auto") == 0) {
+      if (iarg+2 > narg) error->all(FLERR,"Illegal kspace_modify command");
+      if (strcmp(arg[iarg+1],"yes") == 0) auto_disp_flag = 1;
+      else if (strcmp(arg[iarg+1],"no") == 0) auto_disp_flag = 0;
+      else error->all(FLERR,"Illegal kspace_modify command");
+      iarg += 2;
     } else error->all(FLERR,"Illegal kspace_modify command");
   }
 }

src/kspace.h

@@ -66,6 +66,7 @@ class KSpace : protected Pointers {
                                     // dispersion solver (force units)
   double accuracy_kspace_6;         // reciprocal space accuracy for 
                                     // dispersion solver (force units)
+  int auto_disp_flag;		    // use automatic paramter generation for pppm/disp
   double two_charge_force;          // force in user units of two point
                                     // charges separated by 1 Angstrom