do not allow single bond/angle/dihedral definitions with illegal atom ID combinations

src/create_bonds.cpp

@@ -75,6 +75,8 @@ void CreateBonds::command(int narg, char **arg)
     btype = force->inumeric(FLERR,arg[1]);
     batom1 = force->tnumeric(FLERR,arg[2]);
     batom2 = force->tnumeric(FLERR,arg[3]);
+    if (batom1 == batom2)
+      error->all(FLERR,"Illegal create_bonds command");
     iarg = 4;
   } else if (strcmp(arg[0],"single/angle") == 0) {
     style = SANGLE;
@@ -83,6 +85,8 @@ void CreateBonds::command(int narg, char **arg)
     aatom1 = force->tnumeric(FLERR,arg[2]);
     aatom2 = force->tnumeric(FLERR,arg[3]);
     aatom3 = force->tnumeric(FLERR,arg[4]);
+    if ((aatom1 == aatom2) || (aatom1 == aatom3) || (aatom2 == aatom3))
+      error->all(FLERR,"Illegal create_bonds command");
     iarg = 5;
   } else if (strcmp(arg[0],"single/dihedral") == 0) {
     style = SDIHEDRAL;
@@ -92,6 +96,9 @@ void CreateBonds::command(int narg, char **arg)
     datom2 = force->tnumeric(FLERR,arg[3]);
     datom3 = force->tnumeric(FLERR,arg[4]);
     datom4 = force->tnumeric(FLERR,arg[5]);
+    if ((datom1 == datom2) || (datom1 == datom3) || (datom1 == datom4) ||
+        (datom2 == datom3) || (datom2 == datom4) || (datom3 == datom4))
+      error->all(FLERR,"Illegal create_bonds command");
     iarg = 6;
   } else error->all(FLERR,"Illegal create_bonds command");