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Added a function to perform a single excitation on cfg and identify the type.

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v1j4y 2021-01-31 21:58:33 +01:00
parent d750915fcf
commit 1a8dc02b5a
1 changed files with 112 additions and 0 deletions
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112
src/determinants/create_excitations.irp.f
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@ -183,6 +183,118 @@ subroutine do_single_excitation_cfg(key_in,key_out,i_hole,i_particle,ok)
end
subroutine do_single_excitation_cfg_with_type(key_in,key_out,i_hole,i_particle,ex_type,ok)
use bitmasks
implicit none
BEGIN_DOC
! Applies the single excitation operator to a configuration
! Returns the type of excitation in ex_type
! where the following convention is used
! 1 = (SOMO -> SOMO) 1 change in Nsomo
! 2 = (DOMO -> VMO) 1 change in Nsomo
! 3 = (SOMO -> VMO) 0 change in Nsomo
! 4 = (DOMO -> SOMO) 0 change in Nsomo
! If the excitation is possible, ok is True
END_DOC
integer, intent(in) :: i_hole,i_particle
integer(bit_kind), intent(in) :: key_in(N_int,2)
integer , intent(out) :: ex_type
logical , intent(out) :: ok
integer :: k,j,i
integer(bit_kind) :: mask
integer(bit_kind) :: key_out(N_int,2)
logical :: isholeSOMO
logical :: isparticleSOMO
logical :: isholeDOMO
logical :: isparticleVMO
ASSERT (i_hole > 0)
ASSERT (i_particle <= mo_num)
ok = .True.
key_out(:,:) = key_in(:,:)
! hole
k = shiftr(i_hole-1,bit_kind_shift)+1
j = i_hole-shiftl(k-1,bit_kind_shift)-1
mask = ibset(0_bit_kind,j)
! Check if the position j is singly occupied
! 1 -> 0 (SOMO)
! 0 0 (DOMO)
if (iand(key_out(k,1),mask) /= 0_bit_kind) then
key_out(k,1) = ibclr(key_out(k,1),j)
isholeSOMO = .True.
! Check if the position j is doubly occupied
! 0 -> 1 (SOMO)
! 1 0 (DOMO)
else if (iand(key_out(k,2),mask) /= 0_bit_kind) then
key_out(k,1) = ibset(key_out(k,1),j)
key_out(k,2) = ibclr(key_out(k,2),j)
isholeDOMO = .True.
! The position j is unoccupied: Not OK
! 0 -> 0 (SOMO)
! 0 0 (DOMO)
else
ok =.False.
return
endif
! particle
k = shiftr(i_particle-1,bit_kind_shift)+1
j = i_particle-shiftl(k-1,bit_kind_shift)-1
mask = ibset(0_bit_kind,j)
! Check if the position j is singly occupied
! 1 -> 0 (SOMO)
! 0 1 (DOMO)
if (iand(key_out(k,1),mask) /= 0_bit_kind) then
key_out(k,1) = ibclr(key_out(k,1),j)
key_out(k,2) = ibset(key_out(k,2),j)
isparticleSOMO = .True.
! Check if the position j is doubly occupied : Not OK
! 0 -> 1 (SOMO)
! 1 0 (DOMO)
else if (iand(key_out(k,2),mask) /= 0_bit_kind) then
ok = .False.
return
! Position at j is unoccupied
! 0 -> 0 (SOMO)
! 0 0 (DOMO)
else
key_out(k,1) = ibset(key_out(k,1),j)
isparticleVMO = .True.
endif
if(isholeSOMO) then
! two possibilities
! particle is SOMO or VMO
if(isparticleSOMO) then
! SOMO -> SOMO
ex_type = 1
else
! SOMO -> VMO
ex_type = 3
endif
else
! two possibilities
! particle is SOMO or VMO
if(isparticleSOMO) then
! DOMO -> SOMO
ex_type = 4
else
! DOMO -> VMO
ex_type = 2
endif
endif
end
subroutine generate_all_singles_cfg(cfg,singles,n_singles,Nint)
implicit none
use bitmasks