quantum-espresso/PW/cft3.f90

72 lines
1.9 KiB
Fortran

!
! Copyright (C) 2001-2004 PWSCF group
! This file is distributed under the terms of the
! GNU General Public License. See the file `License'
! in the root directory of the present distribution,
! or http://www.gnu.org/copyleft/gpl.txt .
!
!
!----------------------------------------------------------------------------
SUBROUTINE cft3( f, n1, n2, n3, nx1, nx2, nx3, sign )
!----------------------------------------------------------------------------
!
! ... sign = +-1 : parallel 3d fft for rho and for the potential
!
! ... sign = +1 : G-space to R-space, output = \sum_G f(G)exp(+iG*R)
! ... fft along z using pencils (cft_1z)
! ... transpose across nodes (fft_scatter)
! ... and reorder
! ... fft along y and x (cft_2xy)
!
! ... sign = -1 : R-space to G-space, output = \int_R f(R)exp(-iG*R)/Omega
! ... fft along x and y (cft_2xy)
! ... transpose across nodes (fft_scatter)
! ... and reorder
! ... fft along z using pencils (cft_1z)
!
USE fft_scalar, ONLY : cfft3d
USE fft_base, ONLY : dfftp
USE fft_parallel, ONLY : tg_cft3s
USE kinds, ONLY : DP
!
IMPLICIT NONE
!
INTEGER, INTENT(IN) :: n1, n2, n3, nx1, nx2, nx3, sign
#if defined (__PARA) && ! defined (__USE_3D_FFT)
COMPLEX(DP), INTENT(INOUT) :: f( dfftp%nnr )
!
CALL tg_cft3s( f, dfftp, sign )
#else
!
COMPLEX(DP), INTENT(INOUT) :: f(nx1*nx2*nx3)
!
!
CALL start_clock( 'cft3' )
!
! ... sign = +-1 : complete 3d fft (for rho and for the potential)
!
IF ( sign == 1 ) THEN
!
CALL cfft3d( f, n1, n2, n3, nx1, nx2, nx3, 1 )
!
ELSE IF ( sign == - 1 ) THEN
!
CALL cfft3d( f, n1, n2, n3, nx1, nx2, nx3, -1 )
!
ELSE
!
CALL errore( 'cft3', 'what should i do?', 1 )
!
ENDIF
!
CALL stop_clock( 'cft3' )
!
#endif
!
RETURN
!
END SUBROUTINE cft3