add code to detect inconistent use of AIREBO/REBO potential files

doc/src/pair_airebo.txt

@@ -36,7 +36,7 @@ pair_style airebo/morse 3.0
 pair_coeff * * ../potentials/CH.airebo-m H C :pre
 
 pair_style rebo
-pair_coeff * * ../potentials/CH.airebo H C :pre
+pair_coeff * * ../potentials/CH.rebo H C :pre
 
 [Description:]
 
@@ -57,7 +57,8 @@ The {rebo} pair style computes the Reactive Empirical Bond Order (REBO)
 Potential of "(Brenner)"_#Brenner. Note that this is the so-called
 2nd generation REBO from 2002, not the original REBO from 1990.
 As discussed below, 2nd generation REBO is closely related to the
-initial AIREBO; it is just a subset of the potential energy terms.
+initial AIREBO; it is just a subset of the potential energy terms
+with a few slightly different parameters
 
 The AIREBO potential consists of three terms:
 
@@ -113,12 +114,12 @@ various dihedral angle preferences in hydrocarbon configurations.
 :line
 
 Only a single pair_coeff command is used with the {airebo}, {airebo}
-or {rebo} style which specifies an AIREBO or AIREBO-M potential file
-with parameters for C and H.  Note that the {rebo} style in LAMMPS
-uses the same AIREBO-formatted potential file.  These are mapped to
-LAMMPS atom types by specifying N additional arguments after the
-filename in the pair_coeff command, where N is the number of LAMMPS
-atom types:
+or {rebo} style which specifies an AIREBO, REBO, or AIREBO-M potential
+file with parameters for C and H.  Note that as of LAMMPS version
+15 November 2018 the {rebo} style in LAMMPS uses its own potential
+file (CH.rebo).  These are mapped to LAMMPS atom types by specifying
+N additional arguments after the filename in the pair_coeff command,
+where N is the number of LAMMPS atom types:
 
 filename
 N element names = mapping of AIREBO elements to atom types :ul

src/MANYBODY/pair_airebo.cpp

@@ -49,7 +49,8 @@ using namespace MathSpecial;
 
 /* ---------------------------------------------------------------------- */
 
-PairAIREBO::PairAIREBO(LAMMPS *lmp) : Pair(lmp)
+PairAIREBO::PairAIREBO(LAMMPS *lmp)
+  : Pair(lmp), variant(AIREBO)
 {
   single_enable = 0;
   restartinfo = 0;
@@ -3368,14 +3369,38 @@ void PairAIREBO::read_file(char *filename)
     FILE *fp = force->open_potential(filename);
     if (fp == NULL) {
       char str[128];
-      if (morseflag)
-        snprintf(str,128,"Cannot open AIREBO-M potential file %s",filename);
-      else
+      switch (variant) {
+
+      case AIREBO:
         snprintf(str,128,"Cannot open AIREBO potential file %s",filename);
+        break;
+
+      case REBO_2:
+        snprintf(str,128,"Cannot open REBO2 potential file %s",filename);
+        break;
+
+      case AIREBO_M:
+        snprintf(str,128,"Cannot open AIREBO-M potential file %s",filename);
+        break;
+
+      default:
+        snprintf(str,128,"Unknown REBO style variant %d",variant);
+      }
       error->one(FLERR,str);
     }
 
-    // skip initial comment lines
+    // skip initial comment line and check for potential file style identifier comment
+
+    fgets(s,MAXLINE,fp);
+    fgets(s,MAXLINE,fp);
+
+    if (((variant == AIREBO) && (strncmp(s,"# AIREBO ",9) != 0))
+        || ((variant == REBO_2) && (strncmp(s,"# REBO2 ",8) != 0))
+        || ((variant == AIREBO_M) && (strncmp(s,"# AIREBO-M ",11) != 0))) {
+      error->one(FLERR,"Potential file does not match AIREBO/REBO style variant");
+    }
+
+    // skip remaining comments
 
     while (1) {
       fgets(s,MAXLINE,fp);

src/MANYBODY/pair_airebo.h

@@ -38,10 +38,12 @@ class PairAIREBO : public Pair {
   double init_one(int, int);
   double memory_usage();
 
- protected:
+  enum { AIREBO, REBO_2, AIREBO_M }; // for telling class variants apart in shared code
+
+protected:
   int *map;                        // 0 (C), 1 (H), or -1 (NULL) for each type
 
-  int me;
+  int me,variant;
   int ljflag,torflag;              // 0/1 if LJ/Morse,torsion terms included
   int morseflag;                   // 1 if Morse instead of LJ for non-bonded
 

src/MANYBODY/pair_airebo_morse.cpp

@@ -19,7 +19,9 @@ using namespace LAMMPS_NS;
 
 /* ---------------------------------------------------------------------- */
 
-PairAIREBOMorse::PairAIREBOMorse(LAMMPS *lmp) : PairAIREBO(lmp) {}
+PairAIREBOMorse::PairAIREBOMorse(LAMMPS *lmp) : PairAIREBO(lmp) {
+  variant = AIREBO_M;
+}
 
 /* ----------------------------------------------------------------------
    global settings

src/MANYBODY/pair_rebo.cpp

@@ -18,7 +18,9 @@ using namespace LAMMPS_NS;
 
 /* ---------------------------------------------------------------------- */
 
-PairREBO::PairREBO(LAMMPS *lmp) : PairAIREBO(lmp) {}
+PairREBO::PairREBO(LAMMPS *lmp) : PairAIREBO(lmp) {
+  variant = REBO_2;
+}
 
 /* ----------------------------------------------------------------------
    global settings