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qp2/src/determinants/generate_cas_space.irp.f
Anthony Scemama bc042cefa2
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Fixed previous commit
2024-01-10 11:14:49 +01:00

88 lines
2.0 KiB
Fortran

subroutine generate_cas_space
use bitmasks
implicit none
BEGIN_DOC
! Generates the CAS space
END_DOC
integer :: i, sze, ncore, n_alpha_act, n_beta_act
integer(bit_kind) :: o(N_int)
integer(bit_kind) :: u
integer :: mo_list(elec_alpha_num)
integer :: k,n,m
integer(bit_kind) :: t, t1, t2
call list_to_bitstring(o, list_core_inact, n_core_inact_orb, N_int)
! Count number of active electrons
n_alpha_act = 0
n_beta_act = 0
do i=1, n_act_orb
if (list_act(i) <= elec_alpha_num) then
n_alpha_act += 1
endif
if (list_act(i) <= elec_beta_num) then
n_beta_act += 1
endif
enddo
if (n_act_orb > 64) then
stop 'More than 64 active MOs'
endif
print *, ''
print *, 'CAS(', n_alpha_act+n_beta_act, ', ', n_act_orb, ')'
print *, ''
n_det_alpha_unique = binom_int(n_act_orb, n_alpha_act)
TOUCH n_det_alpha_unique
n = n_alpha_act
u = shiftl(1_bit_kind,n) - 1_bit_kind
k=0
do while (u < shiftl(1_bit_kind,n_act_orb))
k = k+1
call bitstring_to_list(u, mo_list, m, 1)
do i=1,m
mo_list(i) = list_act( mo_list(i) )
enddo
call list_to_bitstring(psi_det_alpha_unique(1,k), mo_list, m, N_int)
do i=1,N_int
psi_det_alpha_unique(i,k) = ior(psi_det_alpha_unique(i,k), o(i))
enddo
t = ior(u,u-1)
t1 = t+1
t2 = shiftr((iand(not(t),t1)-1), trailz(u)+1)
u = ior(t1,t2)
enddo
n_det_beta_unique = binom_int(n_act_orb, n_beta_act)
TOUCH n_det_beta_unique
n = n_beta_act
u = shiftl(1_bit_kind,n) -1_bit_kind
k=0
do while (u < shiftl(1_bit_kind,n_act_orb))
k = k+1
call bitstring_to_list(u, mo_list, m, 1)
do i=1,m
mo_list(i) = list_act( mo_list(i) )
enddo
call list_to_bitstring(psi_det_beta_unique(1,k), mo_list, m, N_int)
do i=1,N_int
psi_det_beta_unique(i,k) = ior(psi_det_beta_unique(i,k), o(i))
enddo
t = ior(u,u-1)
t1 = t+1
t2 = shiftr((iand(not(t),t1)-1), trailz(u)+1)
u = ior(t1,t2)
enddo
call generate_all_alpha_beta_det_products
print *, 'Ndet = ', N_det
end