mirror of https://gitlab.com/QEF/q-e.git
181 lines
4.5 KiB
Fortran
181 lines
4.5 KiB
Fortran
!
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! Copyright (C) 2001-2007 Quantum-ESPRESSO group
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! This file is distributed under the terms of the
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! GNU General Public License. See the file `License'
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! in the root directory of the present distribution,
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! or http://www.gnu.org/copyleft/gpl.txt .
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!
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#include "f_defs.h"
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!
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!----------------------------------------------------------------------------
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SUBROUTINE cdiagh( n, h, ldh, e, v )
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!----------------------------------------------------------------------------
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!
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! ... calculates all the eigenvalues and eigenvectors of a complex
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! ... hermitean matrix H. On output, the matrix is unchanged
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!
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USE kinds, ONLY : DP
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USE mp_global, ONLY : nproc, npool, nproc_pool, me_pool, &
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root_pool, intra_pool_comm, my_image_id
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USE mp, ONLY : mp_bcast
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!
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IMPLICIT NONE
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!
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! ... on INPUT
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!
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INTEGER :: n, ldh
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! dimension of the matrix to be diagonalized
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! leading dimension of h, as declared in the calling pgm unit
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COMPLEX(DP) :: h(ldh,n)
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! matrix to be diagonalized
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!
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! ... on OUTPUT
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!
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REAL(DP) :: e(n) ! eigenvalues
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COMPLEX(DP) :: v(ldh,n) ! eigenvectors (column-wise)
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!
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CALL start_clock( 'diagh' )
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!
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#if defined (__ESSL)
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CALL cdiagh_aix()
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#else
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CALL cdiagh_lapack( v, e )
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#endif
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!
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CALL stop_clock( 'diagh' )
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!
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RETURN
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!
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CONTAINS
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!
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! ... internal procedures
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!
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#if defined (__ESSL)
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!
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!-----------------------------------------------------------------------
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SUBROUTINE cdiagh_aix()
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!-----------------------------------------------------------------------
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!
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IMPLICIT NONE
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!
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! ... local variables (ESSL version)
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!
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INTEGER :: naux, i, j, ij
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COMPLEX(DP), ALLOCATABLE :: hp(:), aux(:)
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!
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!
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naux = 4 * n
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!
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ALLOCATE( hp( n * (n + 1) / 2 ) )
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ALLOCATE( aux( naux ) )
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!
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! ... copy to upper triangular packed matrix
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!
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ij = 0
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DO j = 1, n
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DO i = 1, j
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ij = ij + 1
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hp(ij) = h(i,j)
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END DO
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END DO
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!
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! ... only the first processor diagonalize the matrix
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!
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IF ( me_pool == root_pool ) THEN
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!
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CALL ZHPEV( 21, hp, e, v, ldh, n, aux, naux )
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!
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END IF
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!
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CALL mp_bcast( e, root_pool, intra_pool_comm )
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CALL mp_bcast( v, root_pool, intra_pool_comm )
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!
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DEALLOCATE( aux )
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DEALLOCATE( hp )
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!
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RETURN
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!
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END SUBROUTINE cdiagh_aix
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!
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#else
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!
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!-----------------------------------------------------------------------
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SUBROUTINE cdiagh_lapack( v, e )
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!-----------------------------------------------------------------------
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!
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IMPLICIT NONE
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!
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REAL(DP) :: e(n) ! eigenvalues
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COMPLEX(DP) :: v(ldh,n)
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!
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! ... local variables (LAPACK version)
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!
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INTEGER :: lwork, nb, info
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REAL(DP), ALLOCATABLE :: rwork(:)
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COMPLEX(DP), ALLOCATABLE :: work(:)
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!
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INTEGER, EXTERNAL :: ILAENV
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! ILAENV returns optimal block size "nb"
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!
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! ... check for the block size
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!
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nb = ILAENV( 1, 'ZHETRD', 'U', n, - 1, - 1, - 1 )
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!
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IF ( nb < 1 ) nb = MAX( 1, n )
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!
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IF ( nb == 1 .OR. nb >= n ) THEN
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!
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lwork = 2 * n - 1
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!
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ELSE
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!
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lwork = ( nb + 1 ) * n
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!
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END IF
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!
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! ... only the first processor diagonalize the matrix
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!
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IF ( me_pool == root_pool ) THEN
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!
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! ... allocate workspace
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!
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#ifdef __PGI
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! workaround for PGI compiler bug
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!
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v(1:ldh,1:n) = h(1:ldh,1:n)
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#else
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v = h
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#endif
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!
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ALLOCATE( work( lwork ) )
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ALLOCATE( rwork( 3 * n - 2 ) )
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!
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CALL ZHEEV( 'V', 'U', n, v, ldh, e, work, lwork, rwork, info )
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!
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CALL errore( 'cdiagh', 'diagonalization (ZHEEV) failed', ABS( info ) )
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!
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! ... deallocate workspace
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!
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DEALLOCATE( rwork )
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DEALLOCATE( work )
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!
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END IF
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!
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#ifdef __PGI
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! workaround for PGI compiler bug
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!
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CALL mp_bcast( e(1:n), root_pool, intra_pool_comm )
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CALL mp_bcast( v(1:ldh,1:n), root_pool, intra_pool_comm )
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#else
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CALL mp_bcast( e, root_pool, intra_pool_comm )
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CALL mp_bcast( v, root_pool, intra_pool_comm )
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#endif
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!
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RETURN
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!
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END SUBROUTINE cdiagh_lapack
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!
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#endif
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!
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END SUBROUTINE cdiagh
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