********>Bugfix 10:

Author: David S. Cerutti

Date: August 5, 2017

Programs: pmemd, pmemd.cuda

Description: fixes a vulnerability that would have allowed LJ 12-6-4 to be
             applied with incompatible options.

-------------------------------------------------------------------------------

 src/pmemd/src/mdin_ctrl_dat.F90 | 17 ++++++++++-------
 src/pmemd/src/prmtop_dat.F90    |  3 +++
 2 files changed, 13 insertions(+), 7 deletions(-)

diff --git src/pmemd/src/mdin_ctrl_dat.F90 src/pmemd/src/mdin_ctrl_dat.F90
index aceefab..da73216 100644
--- src/pmemd/src/mdin_ctrl_dat.F90
+++ src/pmemd/src/mdin_ctrl_dat.F90
@@ -2226,12 +2226,6 @@ subroutine validate_mdin_ctrl_dat(remd_method)
     inerr = 1
   end if
 
-  if (lj1264 .gt. 0) then
-    write(mdout, '(a)') 'CUDA (GPU): Implementation does not support 12-6-4 LJ potential.'
-    write(mdout, '(a)') '            Require lj1264 == 0.'
-    inerr = 1
-  end if
-
   !Check the size of the cutoff with respect to the system size.
   if (ntb == 0) then
     !Check not fully implemented. Ideally this check should loop over the current
@@ -2349,26 +2343,35 @@ subroutine post_prm_validate_mdin_ctrl_dat
   if (lj1264 .eq. 1) then
 #ifdef CUDA
     write(mdout, '(a)') 'CUDA (GPU): Implementation does not support 12-6-4 LJ potential.'
-    write(mdout, '(a)') '            Require lj1264 == 0.'
+    write(mdout, '(a)') '            The topology contains 12-6-4 coefficients and must be &
+                        &changed.'
     inerr = 1
 #endif
     if (fswitch .gt. 0) then
       write(mdout, '(2a)') error_hdr, 'fswitch and lj1264 are incompatible!'
+      write(mdout, '(a)') '            The topology contains 12-6-4 coefficients and must be &
+                          &changed.'
       inerr = 1
     end if
     if (using_gb_potential) then
       write(mdout, '(2a)') error_hdr, 'Generalized born is incompatible with &
                            &the 12-6-4 potential'
+      write(mdout, '(a)') '            The topology contains 12-6-4 coefficients and must be &
+                          &changed.'
       inerr = 1
     end if
     if (ips .ne. 0) then
       write(mdout, '(2a)') error_hdr, 'IPS and the 12-6-4 LJ potential &
                            &are incompatible'
+      write(mdout, '(a)') '            The topology contains 12-6-4 coefficients and must be &
+                          &changed.'
       inerr = 1
     end if
     if (icfe .ne. 0) then
       write(mdout, '(2a)') error_hdr, 'The 12-6-4 potential is incompatible &
                            &with TI in pmemd'
+      write(mdout, '(a)') '            The topology contains 12-6-4 coefficients and must be &
+                          &changed.'
       inerr = 1
     end if
   end if
diff --git src/pmemd/src/prmtop_dat.F90 src/pmemd/src/prmtop_dat.F90
index 7c9a47a..629a262 100644
--- src/pmemd/src/prmtop_dat.F90
+++ src/pmemd/src/prmtop_dat.F90
@@ -493,6 +493,9 @@ subroutine init_prmtop_dat(num_ints, num_reals, inpcrd_natom)
 
   end if
 
+  ! Check Lennard-Jones 12-6-4 functionality
+  call post_prm_validate_mdin_ctrl_dat
+
 !BEGIN DBG
 ! nxt_atm = 1
 ! do i = 1, nspm