********> update.9

Authors: Vinicius Wilian D. Cruzeiro

Date: May 21, 2018

Programs: sander

Description: Adds an error message when users run REMD and the box sizes are not the same across all replicas.

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

 AmberTools/src/sander/mdread2.F90 | 40 +++++++++++++++++++++++++++++++++++++++
 1 file changed, 40 insertions(+)

diff --git AmberTools/src/sander/mdread2.F90 AmberTools/src/sander/mdread2.F90
index 97df3f5..cceaa97 100644
--- AmberTools/src/sander/mdread2.F90
+++ AmberTools/src/sander/mdread2.F90
@@ -105,6 +105,8 @@
    integer ist(MPI_STATUS_SIZE), partner, nbonh_c, num_noshake_c
    integer nquant_c, noshake_overlap_c
    integer crggp( natom )
+   _REAL_ val
+   _REAL_, allocatable :: repvals(:)
 #  ifdef CRAY_PVP
 #     define MPI_DOUBLE_PRECISION MPI_REAL8
 #  endif
@@ -687,6 +689,44 @@
       9006 format (5x,'Cutoff=',f9.3,3x,'Tol   =',e9.3)
       9007 format (5x,'Ewald Coefficient =',f9.5)
    end if
+   
+#ifdef MPI
+  ! Prints an error if REMD is to be performed with different cell sizes across
+  ! the different replicas
+  if (rem .ne. 0 .and. ntp .eq. 0) then
+    allocate(repvals(numgroup), stat=ierr)
+    REQUIRE(ierr == 0)
+    do i = 1, 6
+       repvals(:) = 0.d0
+       if (i .eq. 1) then
+         val = a
+       else if (i .eq. 2) then
+         val = b
+       else if (i .eq. 3) then
+         val = c
+       else if (i .eq. 4) then
+         val = alpha
+       else if (i .eq. 5) then
+         val = beta
+       else if (i .eq. 6) then
+         val = gamma
+       end if
+       call mpi_allgather(val, 1, mpi_double_precision, &
+                          repvals, 1, mpi_double_precision, &
+                          commmaster, ierr)
+       do j = 2, numgroup
+         if (abs(repvals(j)-repvals(1)) .gt. 1.0d-5) then
+           write(6,'(a,a,a)') error_hdr, "The box sizes do not match for all REMD replicas."
+           write(6,'(11x,a)') "This can happen, for example, if you are using different input coordinate files"
+           write(6,'(11x,a)') "for the different replicas and these structures come from a NPT run."
+           write(6,'(11x,a)') "Make sure the box lengths and angles are the same for all replicas in all input"
+           write(6,'(11x,a)') "coordinate files."
+           FATAL_ERROR
+         end if
+       end do
+    end do
+  end if
+#endif
 
 !---- QMMM Options ----