Added protection against using charges without full_energy

git-svn-id: svn://svn.icms.temple.edu/lammps-ro/trunk@13539 f3b2605a-c512-4ea7-a41b-209d697bcdaa

doc/fix_gcmc.html

@@ -218,7 +218,8 @@ potential energy calculations, including the following:
 <LI>  many-body pair styles
 <LI>  hybrid pair styles
 <LI>  eam pair styles
-<LI>  triclinic systems 
+<LI>  triclinic systems
+<LI>  charged systems (b/c single() function for Coulombic pair styles requires an atom index to look up charges) 
 <LI>  need to include potential energy contributions from other fixes 
 </UL>
 <P>In these cases, LAMMPS will automatically apply the <I>full_energy</I>

doc/fix_gcmc.txt

@@ -203,7 +203,8 @@ potential energy calculations, including the following:
   many-body pair styles
   hybrid pair styles
   eam pair styles
-  triclinic systems 
+  triclinic systems
+  charged systems (b/c single() function for Coulombic pair styles requires an atom index to look up charges) 
   need to include potential energy contributions from other fixes :ul
 
 In these cases, LAMMPS will automatically apply the {full_energy}