--- trunk/OOPSE/libmdtools/calc_gb.F90	2003/07/15 17:10:50	611
+++ trunk/OOPSE/libmdtools/calc_gb.F90	2003/08/27 16:25:11	730
@@ -51,6 +51,7 @@ contains
        do_pot, do_stress)
     
     integer, intent(in) :: atom1, atom2
+    integer :: id1, id2
     real (kind=dp), intent(inout) :: r, r2
     real (kind=dp), dimension(3), intent(in) :: d
     real (kind=dp) :: pot
@@ -352,8 +353,17 @@ contains
 #endif
     
     if (do_stress) then          
-       if (molMembershipList(atom1) .ne. molMembershipList(atom2)) then
+
+#ifdef IS_MPI
+          id1 = tagRow(atom1)
+          id2 = tagColumn(atom2)
+#else
+          id1 = atom1
+          id2 = atom2
+#endif                 
 
+       if (molMembershipList(id1) .ne. molMembershipList(id2)) then
+
           ! because the d vector is the rj - ri vector, and 
           ! because dUdx, dUdy, dUdz are the force on atom i, we need a
           ! negative sign here: