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!
! Copyright (C) 2002-2009 Quantum ESPRESSO 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 .
!
!------------------------------------------------------------------------------!
MODULE electrons_base
!------------------------------------------------------------------------------!
USE kinds, ONLY: DP
!
IMPLICIT NONE
SAVE
INTEGER :: nbnd = 0 ! number electronic bands, each band contains
! two spin states
INTEGER :: nbndx = 0 ! array dimension nbndx >= nbnd
INTEGER :: nspin = 0 ! nspin = number of spins (1=no spin, 2=LSDA)
INTEGER :: nel(2) = 0 ! number of electrons (up, down)
INTEGER :: nelt = 0 ! total number of electrons ( up + down )
INTEGER :: nupdwn(2) = 0 ! number of states with spin up (1) and down (2)
INTEGER :: iupdwn(2) = 0 ! first state with spin (1) and down (2)
INTEGER :: nudx = 0 ! max (nupdw(1),nupdw(2))
INTEGER :: nbsp = 0 ! total number of electronic states
! (nupdwn(1)+nupdwn(2))
INTEGER :: nbspx = 0 ! array dimension nbspx >= nbsp
!
INTEGER :: nupdwn_bgrp(2) = 0 ! number of states with spin up (1) and down (2) in this band group
INTEGER :: iupdwn_bgrp(2) = 0 ! first state with spin (1) and down (2) in this band group
INTEGER :: nudx_bgrp = 0 ! max (nupdw_bgrp(1),nupdw_bgrp(2)) in this band group
INTEGER :: nbsp_bgrp = 0 ! total number of electronic states
! (nupdwn_bgrp(1)+nupdwn_bgrp(2)) in this band group
INTEGER :: nbspx_bgrp = 0 ! array dimension nbspx_bgrp >= nbsp_bgrp local to the band group
INTEGER :: i2gupdwn_bgrp(2)= 0 ! global index of the first local band
LOGICAL :: telectrons_base_initval = .FALSE.
LOGICAL :: keep_occ = .FALSE. ! if .true. when reading restart file keep
! the occupations calculated in initval
REAL(DP), ALLOCATABLE :: f(:) ! occupation numbers ( at gamma )
REAL(DP) :: qbac = 0.0_DP ! background neutralizing charge
INTEGER, ALLOCATABLE :: ispin(:) ! spin of each state
REAL(DP), ALLOCATABLE :: f_bgrp(:) ! occupation numbers ( at gamma )
INTEGER, ALLOCATABLE :: ispin_bgrp(:) ! spin of each state
INTEGER, ALLOCATABLE :: ibgrp_g2l(:) ! local index of the i-th global band index
!
!------------------------------------------------------------------------------!
CONTAINS
!------------------------------------------------------------------------------!
SUBROUTINE electrons_base_initval( zv_ , na_ , nsp_ , nbnd_ , nspin_ , &
occupations_ , f_inp, tot_charge_, tot_magnetization_ )
USE constants, ONLY : eps8
USE io_global, ONLY : stdout
REAL(DP), INTENT(IN) :: zv_ (:), tot_charge_
REAL(DP), INTENT(IN) :: f_inp(:,:)
REAL(DP), INTENT(IN) :: tot_magnetization_
INTEGER, INTENT(IN) :: na_ (:) , nsp_
INTEGER, INTENT(IN) :: nbnd_ , nspin_
CHARACTER(LEN=*), INTENT(IN) :: occupations_
REAL(DP) :: nelec, nelup, neldw, ocp, fsum
INTEGER :: iss, i, in
nspin = nspin_
!
! ... set nelec
!
nelec = 0.0_DP
DO i = 1, nsp_
nelec = nelec + na_ ( i ) * zv_ ( i )
END DO
nelec = nelec - tot_charge_
!
! ... set nelup/neldw
!
nelup = 0._dp
neldw = 0._dp
call set_nelup_neldw (tot_magnetization_, nelec, nelup, neldw )
IF( ABS( nelec - ( nelup + neldw ) ) > eps8 ) THEN
CALL errore(' electrons_base_initval ',' inconsistent n. of electrons ', 2 )
END IF
!
! Compute the number of bands
!
IF( nbnd_ /= 0 ) THEN
nbnd = nbnd_ ! nbnd is given from input
ELSE
nbnd = NINT( MAX( nelup, neldw ) ) ! take the maximum between up and down states
END IF
IF( nelec < 1 ) THEN
CALL errore(' electrons_base_initval ',' nelec less than 1 ', 1 )
END IF
!
IF( ABS( NINT( nelec ) - nelec ) > eps8 ) THEN
CALL errore(' electrons_base_initval ',' nelec must be integer', 2 )
END IF
!
IF( nbnd < 1 ) &
CALL errore(' electrons_base_initval ',' nbnd out of range ', 1 )
!
IF ( nspin /= 1 .AND. nspin /= 2 ) THEN
WRITE( stdout, * ) 'nspin = ', nspin
CALL errore( ' electrons_base_initval ', ' nspin out of range ', 1 )
END IF
IF( MOD( nbnd, 2 ) == 0 ) THEN
nbspx = nbnd * nspin
ELSE
nbspx = ( nbnd + 1 ) * nspin
END IF
ALLOCATE( f ( nbspx ) )
ALLOCATE( ispin ( nbspx ) )
f = 0.0_DP
ispin = 0
iupdwn ( 1 ) = 1
nel = 0
SELECT CASE ( TRIM(occupations_) )
CASE ('bogus')
!
! bogus to ensure \sum_i f_i = Nelec (nelec is integer)
!
f ( : ) = nelec / nbspx
nel (1) = nint( nelec )
nupdwn (1) = nbspx
if ( nspin == 2 ) then
!
! bogus to ensure Nelec = Nup + Ndw
!
nel (1) = ( nint(nelec) + 1 ) / 2
nel (2) = nint(nelec) / 2
nupdwn (1)=nbnd
nupdwn (2)=nbnd
iupdwn (2)=nbnd+1
end if
!
keep_occ = .true.
!
CASE ('from_input')
!
! occupancies have been read from input
!
! count electrons
!
IF( nspin == 1 ) THEN
nelec = SUM( f_inp( :, 1 ) )
nelup = nelec / 2.0_DP
neldw = nelec / 2.0_DP
ELSE
nelup = SUM ( f_inp ( :, 1 ) )
neldw = SUM ( f_inp ( :, 2 ) )
nelec = nelup + neldw
END IF
!
! consistency check
!
IF( nspin == 1 ) THEN
IF( f_inp( 1, 1 ) <= 0.0_DP ) &
CALL errore(' electrons_base_initval ',' Zero or negative occupation are not allowed ', 1 )
ELSE
IF( f_inp( 1, 1 ) < 0.0_DP ) &
CALL errore(' electrons_base_initval ',' Zero or negative occupation are not allowed ', 1 )
IF( f_inp( 1, 2 ) < 0.0_DP ) &
CALL errore(' electrons_base_initval ',' Zero or negative occupation are not allowed ', 1 )
IF( ( f_inp( 1, 1 ) + f_inp( 1, 2 ) ) == 0.0_DP ) &
CALL errore(' electrons_base_initval ',' Zero or negative occupation are not allowed ', 1 )
END IF
DO i = 2, nbnd
IF( nspin == 1 ) THEN
IF( f_inp( i, 1 ) > 0.0_DP .AND. f_inp( i-1, 1 ) <= 0.0_DP ) &
CALL errore(' electrons_base_initval ',' Zero or negative occupation are not allowed ', 1 )
ELSE
IF( f_inp( i, 1 ) > 0.0_DP .AND. f_inp( i-1, 1 ) <= 0.0_DP ) &
CALL errore(' electrons_base_initval ',' Zero or negative occupation are not allowed ', 1 )
IF( f_inp( i, 2 ) > 0.0_DP .AND. f_inp( i-1, 2 ) <= 0.0_DP ) &
CALL errore(' electrons_base_initval ',' Zero or negative occupation are not allowed ', 1 )
END IF
END DO
!
! count bands
!
nupdwn (1) = 0
nupdwn (2) = 0
DO i = 1, nbnd
IF( nspin == 1 ) THEN
IF( f_inp( i, 1 ) > 0.0_DP ) nupdwn (1) = nupdwn (1) + 1
ELSE
IF( f_inp( i, 1 ) > 0.0_DP ) nupdwn (1) = nupdwn (1) + 1
IF( f_inp( i, 2 ) > 0.0_DP ) nupdwn (2) = nupdwn (2) + 1
END IF
END DO
!
if( nspin == 1 ) then
nel (1) = nint( nelec )
iupdwn (1) = 1
else
nel (1) = nint(nelup)
nel (2) = nint(neldw)
iupdwn (1) = 1
iupdwn (2) = nupdwn (1) + 1
end if
!
DO iss = 1, nspin
DO in = iupdwn ( iss ), iupdwn ( iss ) - 1 + nupdwn ( iss )
f( in ) = f_inp( in - iupdwn ( iss ) + 1, iss )
END DO
END DO
!
CASE ('fixed')
if( nspin == 1 ) then
nel(1) = nint(nelec)
nupdwn(1) = nbnd
iupdwn(1) = 1
else
IF ( nelup + neldw /= nelec ) THEN
CALL errore(' electrons_base_initval ',' wrong # of up and down spin', 1 )
END IF
nel(1) = nint(nelup)
nel(2) = nint(neldw)
nupdwn(1) = nint(nelup)
nupdwn(2) = nint(neldw)
iupdwn(1) = 1
iupdwn(2) = nupdwn(1) + 1
end if
! if( (nspin == 1) .and. MOD( nint(nelec), 2 ) /= 0 ) &
! CALL errore(' electrons_base_initval ', &
! ' must use nspin=2 for odd number of electrons', 1 )
! ocp = 2 for spinless systems, ocp = 1 for spin-polarized systems
ocp = 2.0_DP / nspin
!
! default filling: attribute ocp electrons to each states
! until the good number of electrons is reached
do iss = 1, nspin
fsum = 0.0_DP
do in = iupdwn ( iss ), iupdwn ( iss ) - 1 + nupdwn ( iss )
if ( fsum + ocp < nel ( iss ) + 0.0001_DP ) then
f (in) = ocp
else
f (in) = max( nel ( iss ) - fsum, 0.0_DP )
end if
fsum = fsum + f(in)
end do
end do
!
CASE ('ensemble','ensemble-dft','edft')
if ( nspin == 1 ) then
!
f ( : ) = nelec / nbnd
nel (1) = nint(nelec)
nupdwn (1) = nbnd
!
else
!
if (nelup.ne.0) then
if ((nelup+neldw).ne.nelec) then
CALL errore(' electrons_base_initval ',' nelup+neldw .ne. nelec', 1 )
end if
nel (1) = nelup
nel (2) = neldw
else
nel (1) = ( nint(nelec) + 1 ) / 2
nel (2) = nint(nelec) / 2
end if
!
nupdwn (1) = nbnd
nupdwn (2) = nbnd
iupdwn (2) = nbnd+1
!
do iss = 1, nspin
do i = iupdwn ( iss ), iupdwn ( iss ) - 1 + nupdwn ( iss )
f (i) = nel (iss) / DBLE (nupdwn (iss))
end do
end do
!
end if
CASE DEFAULT
CALL errore(' electrons_base_initval ',' occupation method not implemented', 1 )
END SELECT
do iss = 1, nspin
do in = iupdwn(iss), iupdwn(iss) - 1 + nupdwn(iss)
ispin(in) = iss
end do
end do
nbndx = nupdwn (1)
nudx = nupdwn (1)
nbsp = nupdwn (1) + nupdwn (2)
IF ( nspin == 1 ) THEN
nelt = nel(1)
ELSE
nelt = nel(1) + nel(2)
END IF
IF( nupdwn(1) < nupdwn(2) ) &
CALL errore(' electrons_base_initval ',' nupdwn(1) should be greater or equal nupdwn(2) ', 1 )
IF( nbnd < nupdwn(1) ) &
CALL errore(' electrons_base_initval ',' inconsistent nbnd, should be .GE. than nupdwn(1) ', 1 )
IF( nbspx < ( nupdwn(1) * nspin ) ) &
CALL errore(' electrons_base_initval ',' inconsistent nbspx, should be .GE. than nspin * nupdwn(1) ', 1 )
IF( ( 2 * nbnd ) < nelt ) &
CALL errore(' electrons_base_initval ',' too few states ', 1 )
IF( nbsp < INT( nelec * nspin / 2.0_DP ) ) &
CALL errore(' electrons_base_initval ',' too many electrons ', 1 )
telectrons_base_initval = .TRUE.
RETURN
END SUBROUTINE electrons_base_initval
!----------------------------------------------------------------------------
!
subroutine set_nelup_neldw ( tot_magnetization_, nelec_, nelup_, neldw_ )
!
USE kinds, ONLY : DP
USE constants, ONLY : eps8
!
REAL (KIND=DP), intent(IN) :: tot_magnetization_
REAL (KIND=DP), intent(IN) :: nelec_
REAL (KIND=DP), intent(OUT) :: nelup_, neldw_
LOGICAL :: integer_charge, integer_magnetization
!
integer_charge = ( ABS (nelec_ - NINT(nelec_)) < eps8 )
!
IF ( tot_magnetization_ < 0 ) THEN
! default when tot_magnetization is unspecified
IF ( integer_charge) THEN
nelup_ = INT( nelec_ + 1 ) / 2
neldw_ = nelec_ - nelup_
ELSE
nelup_ = nelec_ / 2
neldw_ = nelup_
END IF
ELSE
! tot_magnetization specified in input
!
if ( (tot_magnetization_ > 0) .and. (nspin==1) ) &
CALL errore(' set_nelup_neldw ', &
'tot_magnetization is inconsistent with nspin=1 ', 2 )
integer_magnetization = ( ABS( tot_magnetization_ - &
NINT(tot_magnetization_) ) < eps8 )
IF ( integer_charge .AND. integer_magnetization) THEN
!
! odd tot_magnetization requires an odd number of electrons
! even tot_magnetization requires an even number of electrons
!
if ( ((MOD(NINT(tot_magnetization_),2) == 0) .and. &
(MOD(NINT(nelec_),2)==1)) .or. &
((MOD(NINT(tot_magnetization_),2) == 1) .and. &
(MOD(NINT(nelec_),2)==0)) ) &
CALL infomsg(' set_nelup_neldw ', &
'BEWARE: non-integer number of up and down electrons!' )
!
! ... setting nelup/neldw
!
nelup_ = ( INT(nelec_) + tot_magnetization_ ) / 2
neldw_ = ( INT(nelec_) - tot_magnetization_ ) / 2
ELSE
!
nelup_ = ( nelec_ + tot_magnetization_ ) / 2
neldw_ = ( nelec_ - tot_magnetization_ ) / 2
END IF
END IF
return
end subroutine set_nelup_neldw
!----------------------------------------------------------------------------
SUBROUTINE deallocate_elct()
IF( ALLOCATED( f ) ) DEALLOCATE( f )
IF( ALLOCATED( ispin ) ) DEALLOCATE( ispin )
IF( ALLOCATED( f_bgrp ) ) DEALLOCATE( f_bgrp )
IF( ALLOCATED( ispin_bgrp ) ) DEALLOCATE( ispin_bgrp )
IF( ALLOCATED( ibgrp_g2l ) ) DEALLOCATE( ibgrp_g2l )
telectrons_base_initval = .FALSE.
RETURN
END SUBROUTINE deallocate_elct
!----------------------------------------------------------------------------
SUBROUTINE distribute_bands( nbgrp, my_bgrp_id )
INTEGER, INTENT(IN) :: nbgrp, my_bgrp_id
INTEGER, EXTERNAL :: ldim_block, gind_block
INTEGER :: iss, n1, n2, m1, m2, ilocal, iglobal
!
IF( .NOT. telectrons_base_initval ) &
CALL errore( ' distribute_bands ', ' electrons_base_initval not yet called ', 1 )
nupdwn_bgrp = nupdwn
iupdwn_bgrp = iupdwn
nudx_bgrp = nudx
nbsp_bgrp = nbsp
nbspx_bgrp = nbspx
i2gupdwn_bgrp= 1
DO iss = 1, nspin
nupdwn_bgrp( iss ) = ldim_block( nupdwn( iss ), nbgrp, my_bgrp_id )
i2gupdwn_bgrp( iss ) = gind_block( 1, nupdwn( iss ), nbgrp, my_bgrp_id )
END DO
!
iupdwn_bgrp(1) = 1
IF( nspin > 1 ) THEN
iupdwn_bgrp(2) = iupdwn_bgrp(1) + nupdwn_bgrp( 1 )
END IF
nudx_bgrp = nupdwn_bgrp( 1 )
nbsp_bgrp = nupdwn_bgrp( 1 ) + nupdwn_bgrp ( 2 )
nbspx_bgrp = nbsp_bgrp
IF( MOD( nbspx_bgrp, 2 ) /= 0 ) nbspx_bgrp = nbspx_bgrp + 1
ALLOCATE( f_bgrp ( nbspx_bgrp ) )
ALLOCATE( ispin_bgrp ( nbspx_bgrp ) )
ALLOCATE( ibgrp_g2l ( nbspx ) )
f_bgrp = 0.0
ispin_bgrp = 0
ibgrp_g2l = 0
!
DO iss = 1, nspin
n1 = iupdwn_bgrp(iss)
n2 = n1 + nupdwn_bgrp(iss) - 1
m1 = iupdwn(iss)+i2gupdwn_bgrp(iss) - 1
m2 = m1 + nupdwn_bgrp(iss) - 1
f_bgrp(n1:n2) = f(m1:m2)
ispin_bgrp(n1:n2) = ispin(m1:m2)
ilocal = n1
DO iglobal = m1, m2
ibgrp_g2l( iglobal ) = ilocal
ilocal = ilocal + 1
END DO
END DO
RETURN
END SUBROUTINE distribute_bands
!------------------------------------------------------------------------------!
END MODULE electrons_base
!------------------------------------------------------------------------------!
|
