Added calbec on a group of bands. It is used in GIPAW with band-parallelization.

git-svn-id: http://qeforge.qe-forge.org/svn/q-e/trunk/espresso@8782 c92efa57-630b-4861-b058-cf58834340f0

PW/src/becmod.f90

@@ -71,6 +71,10 @@ MODULE becmod
   !
   PUBLIC :: bec_type, becp, allocate_bec_type, deallocate_bec_type, calbec, &
             beccopy, becscal
+#ifdef __BANDS
+  PUBLIC :: calbec_bands
+#endif
+
   !
 CONTAINS
   !-----------------------------------------------------------------------
@@ -322,6 +326,66 @@ CONTAINS
     RETURN
     !
   END SUBROUTINE calbec_nc
+
+#ifdef __BANDS
+  !-----------------------------------------------------------------------
+  SUBROUTINE calbec_bands ( npw, beta, psi, betapsi, nbnd, ibnd_start, ibnd_end)
+    !-----------------------------------------------------------------------
+    !
+    ! ... matrix times matrix with summation index (k=1,npw) running on
+    ! ... G-vectors or PWs : betapsi(i,j) = \sum_k beta^*(i,k) psi(k,j)
+    !
+    USE mp_global, ONLY : intra_bgrp_comm, intra_pool_comm
+    USE mp,        ONLY : mp_sum
+
+    IMPLICIT NONE
+    COMPLEX (DP), INTENT (in) :: beta(:,:), psi(:,:)
+    COMPLEX (DP), INTENT (out) :: betapsi(:,:)
+    INTEGER, INTENT (in) :: npw
+    INTEGER, OPTIONAL :: nbnd, ibnd_start, ibnd_end
+    
+    INTEGER :: nkb, npwx, m
+    !
+    nkb = size (beta, 2)
+    IF ( nkb == 0 ) RETURN
+    !
+    CALL start_clock( 'calbec' )
+    npwx= size (beta, 1)
+    IF ( npwx /= size (psi, 1) ) CALL errore ('calbec', 'size mismatch', 1)
+    IF ( npwx < npw ) CALL errore ('calbec', 'size mismatch', 2)
+    IF ( present (nbnd) ) THEN
+        m = nbnd
+    ELSE
+        m = size ( psi, 2)
+    ENDIF
+#ifdef DEBUG
+    WRITE (*,*) 'calbec bands'
+    WRITE (*,*)  nkb, size(betapsi,1), m, size (betapsi, 2), ibnd_start, ibnd_end
+#endif
+    IF ( nkb /= size (betapsi,1) .or. m > size (betapsi, 2) ) &
+      CALL errore ('calbec', 'size mismatch', 3)
+    !
+    IF ( m == 1 ) THEN
+       !
+       CALL ZGEMV( 'C', npw, nkb, (1.0_DP,0.0_DP), beta, npwx, psi, 1, &
+                   (0.0_DP, 0.0_DP), betapsi, 1 )
+       !
+    ELSE
+       !
+       CALL ZGEMM( 'C', 'N', nkb, ibnd_end-ibnd_start+1, npw, (1.0_DP,0.0_DP), &
+                 beta, npwx, psi(1,ibnd_start), npwx, (0.0_DP,0.0_DP), betapsi(1,ibnd_start), nkb )
+       !
+    ENDIF
+    !
+    CALL mp_sum( betapsi( :, 1:m ), intra_bgrp_comm )
+    !
+    CALL stop_clock( 'calbec' )
+    !
+    RETURN
+    !
+  END SUBROUTINE calbec_bands
+#endif
+
   !
   !-----------------------------------------------------------------------
   SUBROUTINE allocate_bec_type ( nkb, nbnd, bec, comm )