--- trunk/OOPSE/libmdtools/do_Forces.F90	2003/04/11 15:16:59	490
+++ trunk/OOPSE/libmdtools/do_Forces.F90	2003/07/01 22:39:53	571
@@ -4,7 +4,7 @@
 
 !! @author Charles F. Vardeman II
 !! @author Matthew Meineke
-!! @version $Id: do_Forces.F90,v 1.15 2003-04-11 15:16:59 gezelter Exp $, $Date: 2003-04-11 15:16:59 $, $Name: not supported by cvs2svn $, $Revision: 1.15 $
+!! @version $Id: do_Forces.F90,v 1.16 2003-07-01 22:39:53 gezelter Exp $, $Date: 2003-07-01 22:39:53 $, $Name: not supported by cvs2svn $, $Revision: 1.16 $
 
 module do_Forces
   use force_globals
@@ -597,21 +597,53 @@ contains
     real (kind = dp), dimension(3) :: q_i
     real (kind = dp), dimension(3) :: q_j
     real ( kind = dp ), intent(out) :: r_sq
-    real( kind = dp ) :: d(3)
-    real( kind = dp ) :: d_old(3)
+    real( kind = dp ) :: d(3), scaled(3)
+    integer i
+
     d(1:3) = q_j(1:3) - q_i(1:3)
-    d_old = d
+
     ! Wrap back into periodic box if necessary
     if ( SimUsesPBC() ) then
        
-       d(1:3) = d(1:3) - box(1:3) * sign(1.0_dp,d(1:3)) * &
-            int(abs(d(1:3)/box(1:3)) + 0.5_dp)
+       if( .not.boxIsOrthorhombic ) then
+          ! calc the scaled coordinates.
+          
+          scaled = matmul(d, HmatInv)
+          
+          ! wrap the scaled coordinates
+
+          do i = 1, 3
+             scaled(i) = scaled(i) - anint(scaled(i))
+          enddo
+
+          ! calc the wrapped real coordinates from the wrapped scaled 
+          ! coordinates
+
+          d = matmul(scaled,Hmat)
+
+       else
+          ! calc the scaled coordinates.
+          
+          do i = 1, 3
+             scaled(i) = d(i) * HmatInv(i,i)
+             
+             ! wrap the scaled coordinates
+             
+             scaled(i) = scaled(i) - anint(scaled(i))
+             
+             ! calc the wrapped real coordinates from the wrapped scaled 
+             ! coordinates
+
+             d(i) = scaled(i)*Hmat(i,i)
+          enddo
+       endif
        
     endif
+    
     r_sq = dot_product(d,d)
-        
+    
   end subroutine get_interatomic_vector
-
+  
   subroutine check_initialization(error)
     integer, intent(out) :: error