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Rewrite get_phase_qp_to_cfg

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This commit is contained in:
Anthony Scemama 2021-02-26 17:28:03 +01:00
parent 1691c74539
commit 52701979ce
1 changed files with 55 additions and 53 deletions
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66
src/csf/sigma_vector.irp.f
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@ -46,7 +46,6 @@
enddo
END_PROVIDER
subroutine get_phase_qp_to_cfg(Ialpha, Ibeta, phaseout)
use bitmasks
implicit none
@ -62,41 +61,44 @@ subroutine get_phase_qp_to_cfg(Ialpha, Ibeta, phaseout)
integer(bit_kind),intent(in) :: Ialpha(N_int)
integer(bit_kind),intent(in) :: Ibeta(N_int)
real*8,intent(out) :: phaseout
integer(bit_kind) :: mask(N_int), deta(N_int), detb(N_int)
integer(bit_kind) :: mask, mask2(N_int), deta(N_int), detb(N_int)
integer :: nbetas
integer :: count, k
if (N_int >1 ) then
stop 'TODO: get_phase_qp_to_cfg '
! Remove the DOMOs
mask2 = IAND(Ialpha,Ibeta)
deta = IEOR(Ialpha,mask2)
detb = IEOR(Ibeta ,mask2)
! Find how many alpha electrons there are in all the N_ints
integer :: Na(N_int)
do k=1,N_int
Na(k) = popcnt(deta(k))
enddo
integer :: shift, ipos, nperm
phaseout = 1.d0
do k=1,N_int
do while(detb(k) /= 0_bit_kind)
! Find the lowest beta electron and clear it
ipos = trailz(detb(k))
detb(k) = ibclr(detb(k),ipos)
! Create a mask will all MOs higher than the beta electron
mask = not(shiftl(1_bit_kind,ipos+1) - 1_bit_kind)
! Apply the mask to the alpha string to count how many electrons to cross
nperm = popcnt( iand(mask, deta(k)) )
! Count how many alpha electrons are above the beta electron in the other integers
nperm = nperm + sum(Na(k+1:N_int))
if (iand(nperm,1) == 1) then
phaseout = -phaseout
endif
nbetas = 0
mask = 0_bit_kind
count = 0
deta = Ialpha
detb = Ibeta
! remove the domos
mask = IAND(deta,detb)
deta = IEOR(deta,mask)
detb = IEOR(detb,mask)
mask = 0
phaseout = 1.0
k = 1
do while((deta(k)).GT.0_8)
mask(k) = ISHFT(1_8,count)
if(POPCNT(IAND(deta(k),mask(k))).EQ.1)then
if(IAND(nbetas,1).EQ.0) then
phaseout *= 1.0d0
else
phaseout *= -1.0d0
endif
deta(k) = IEOR(deta(k),mask(k))
else
if(POPCNT(IAND(detb(k),mask(k))).EQ.1) then
nbetas += 1
detb(k) = IEOR(detb(k),mask(k))
endif
endif
count += 1
enddo
enddo
end subroutine get_phase_qp_to_cfg