--- trunk/OOPSE/libmdtools/do_Forces.F90	2003/03/24 21:55:34	394
+++ trunk/OOPSE/libmdtools/do_Forces.F90	2003/04/01 16:50:14	441
@@ -4,7 +4,7 @@
 
 !! @author Charles F. Vardeman II
 !! @author Matthew Meineke
-!! @version $Id: do_Forces.F90,v 1.4 2003-03-24 21:55:34 gezelter Exp $, $Date: 2003-03-24 21:55:34 $, $Name: not supported by cvs2svn $, $Revision: 1.4 $
+!! @version $Id: do_Forces.F90,v 1.7 2003-04-01 16:50:14 chuckv Exp $, $Date: 2003-04-01 16:50:14 $, $Name: not supported by cvs2svn $, $Revision: 1.7 $
 
 module do_Forces
   use force_globals
@@ -167,7 +167,7 @@ contains
     logical ( kind = 2) :: do_pot_c, do_stress_c
     logical :: do_pot
     logical :: do_stress
-#ifdef IS_MPI
+#ifdef IS_MPI 
     real( kind = DP ) :: pot_local
     integer :: nrow
     integer :: ncol
@@ -189,6 +189,7 @@ contains
     !! initialize local variables  
 
 #ifdef IS_MPI
+    pot_local = 0.0_dp
     nlocal = getNlocal()
     nrow   = getNrow(plan_row)
     ncol   = getNcol(plan_col)
@@ -196,7 +197,7 @@ contains
     nlocal = getNlocal()
     natoms = nlocal
 #endif
-
+   
     call getRcut(rcut,rc2=rcutsq)
     call getRlist(rlist,rlistsq)
     
@@ -277,7 +278,7 @@ contains
                                 
                 if (rijsq <  rcutsq) then
                    call do_pair(i, j, rijsq, d, do_pot, do_stress, &
-                        u_l, A, f, t,pot)
+                        u_l, A, f, t, pot_local)
                 endif
              endif
           enddo inner
@@ -299,7 +300,7 @@ contains
 
                 call get_interatomic_vector(q_Row(:,i), q_Col(:,j), d, rijsq)
                 call do_pair(i, j, rijsq, d, do_pot, do_stress, &
-                     u_l, A, f, t,pot)
+                     u_l, A, f, t, pot_local)
 
              enddo
           endif
@@ -346,7 +347,7 @@ contains
                 
                 if (rijsq <  rcutsq) then
                    call do_pair(i, j, rijsq, d, do_pot, do_stress, &
-                        u_l, A, f, t,pot)
+                        u_l, A, f, t, pot)
                 endif
              endif
           enddo inner
@@ -368,7 +369,7 @@ contains
 
                 call get_interatomic_vector(q(:,i), q(:,j), d, rijsq)
                 call do_pair(i, j, rijsq, d, do_pot, do_stress, &
-                     u_l, A, f, t,pot)
+                     u_l, A, f, t, pot)
 
              enddo
           endif
@@ -381,15 +382,26 @@ contains
     
 #ifdef IS_MPI
     !!distribute forces
-    
-    call scatter(f_Row,f,plan_row3d)
+   
+    f_temp = 0.0_dp
+    call scatter(f_Row,f_temp,plan_row3d)
+    do i = 1,nlocal
+       f(1:3,i) = f(1:3,i) + f_temp(1:3,i)
+    end do
+
+    f_temp = 0.0_dp
     call scatter(f_Col,f_temp,plan_col3d)
     do i = 1,nlocal
        f(1:3,i) = f(1:3,i) + f_temp(1:3,i)
     end do
     
     if (FF_UsesDirectionalAtoms() .and. SimUsesDirectionalAtoms()) then
-       call scatter(t_Row,t,plan_row3d)
+       t_temp = 0.0_dp
+       call scatter(t_Row,t_temp,plan_row3d)
+       do i = 1,nlocal
+          t(1:3,i) = t(1:3,i) + t_temp(1:3,i)
+       end do
+       t_temp = 0.0_dp
        call scatter(t_Col,t_temp,plan_col3d)
        
        do i = 1,nlocal
@@ -400,20 +412,20 @@ contains
     if (do_pot) then
        ! scatter/gather pot_row into the members of my column
        call scatter(pot_Row, pot_Temp, plan_row)
-       
+
        ! scatter/gather pot_local into all other procs
        ! add resultant to get total pot
        do i = 1, nlocal
           pot_local = pot_local + pot_Temp(i)
        enddo
+       
+       pot_Temp = 0.0_DP 
 
-       pot_Temp = 0.0_DP
-
        call scatter(pot_Col, pot_Temp, plan_col)
        do i = 1, nlocal
           pot_local = pot_local + pot_Temp(i)
        enddo
-       
+
     endif    
 #endif
 
@@ -461,7 +473,7 @@ contains
 #ifdef IS_MPI
 
     if (do_pot) then
-       pot = pot_local
+       pot = pot + pot_local
        !! we assume the c code will do the allreduce to get the total potential
        !! we could do it right here if we needed to...
     endif
@@ -484,7 +496,7 @@ contains
     
   end subroutine do_force_loop
 
-  subroutine do_pair(i, j, rijsq, d, do_pot, do_stress, u_l, A, f, t,pot)
+  subroutine do_pair(i, j, rijsq, d, do_pot, do_stress, u_l, A, f, t, pot)
 
     real( kind = dp ) :: pot
     real( kind = dp ), dimension(:,:) :: u_l
@@ -687,7 +699,7 @@ contains
 #else
     unique_id_2 = atom2
 #endif
-    
+
 #ifdef IS_MPI
     !! this situation should only arise in MPI simulations
     if (unique_id_1 == unique_id_2) then
@@ -697,14 +709,18 @@ contains
     
     !! this prevents us from doing the pair on multiple processors
     if (unique_id_1 < unique_id_2) then
-       if (mod(unique_id_1 + unique_id_2,2) == 0) skip_it = .true.
-       return
+       if (mod(unique_id_1 + unique_id_2,2) == 0) then
+          skip_it = .true.
+          return
+       endif
     else                
-       if (mod(unique_id_1 + unique_id_2,2) == 1) skip_it = .true.
-       return
+       if (mod(unique_id_1 + unique_id_2,2) == 1) then 
+          skip_it = .true.
+          return
+       endif
     endif
 #endif
-
+ 
     !! the rest of these situations can happen in all simulations:
     do i = 1, nExcludes_global       
        if ((excludesGlobal(i) == unique_id_1) .or. &
@@ -713,7 +729,7 @@ contains
           return
        endif
     enddo
- 
+
     do i = 1, nExcludes_local
        if (excludesLocal(1,i) == unique_id_1) then
           if (excludesLocal(2,i) == unique_id_2) then