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mirror of https://github.com/QuantumPackage/qp2.git synced 2024-11-07 22:53:52 +01:00
QuantumPackage/src/bitmask/bitmask_cas_routines.irp.f

352 lines
19 KiB
Fortran

use bitmasks
integer function number_of_holes(key_in)
BEGIN_DOC
! Function that returns the number of holes in the inact space
!
! popcnt(
! xor(
! iand(
! reunion_of_core_inact_bitmask(1,1),
! xor(
! key_in(1,1),
! iand(
! key_in(1,1),
! act_bitmask(1,1))
! )
! ),
! reunion_of_core_inact_bitmask(1,1)) )
!
! (key_in && act_bitmask)
! +---------------------+
! electrons in cas xor key_in
! +---------------------------------+
! electrons outside of cas && reunion_of_core_inact_bitmask
! +------------------------------------------------------------------+
! electrons in the core/inact space xor reunion_of_core_inact_bitmask
! +---------------------------------------------------------------------------------+
! holes
END_DOC
implicit none
integer(bit_kind), intent(in) :: key_in(N_int,2)
integer :: i
number_of_holes = 0
if(N_int == 1)then
number_of_holes = number_of_holes &
+ popcnt( xor( iand(reunion_of_core_inact_bitmask(1,1), xor(key_in(1,1),iand(key_in(1,1),act_bitmask(1,1)))), reunion_of_core_inact_bitmask(1,1)) )&
+ popcnt( xor( iand(reunion_of_core_inact_bitmask(1,2), xor(key_in(1,2),iand(key_in(1,2),act_bitmask(1,2)))), reunion_of_core_inact_bitmask(1,2)) )
else if(N_int == 2)then
number_of_holes = number_of_holes &
+ popcnt( xor( iand(reunion_of_core_inact_bitmask(1,1), xor(key_in(1,1),iand(key_in(1,1),act_bitmask(1,1)))), reunion_of_core_inact_bitmask(1,1)) )&
+ popcnt( xor( iand(reunion_of_core_inact_bitmask(1,2), xor(key_in(1,2),iand(key_in(1,2),act_bitmask(1,2)))), reunion_of_core_inact_bitmask(1,2)) )&
+ popcnt( xor( iand(reunion_of_core_inact_bitmask(2,1), xor(key_in(2,1),iand(key_in(2,1),act_bitmask(2,1)))), reunion_of_core_inact_bitmask(2,1)) )&
+ popcnt( xor( iand(reunion_of_core_inact_bitmask(2,2), xor(key_in(2,2),iand(key_in(2,2),act_bitmask(2,2)))), reunion_of_core_inact_bitmask(2,2)) )
else if(N_int == 3)then
number_of_holes = number_of_holes &
+ popcnt( xor( iand(reunion_of_core_inact_bitmask(1,1), xor(key_in(1,1),iand(key_in(1,1),act_bitmask(1,1)))), reunion_of_core_inact_bitmask(1,1)) )&
+ popcnt( xor( iand(reunion_of_core_inact_bitmask(1,2), xor(key_in(1,2),iand(key_in(1,2),act_bitmask(1,2)))), reunion_of_core_inact_bitmask(1,2)) )&
+ popcnt( xor( iand(reunion_of_core_inact_bitmask(2,1), xor(key_in(2,1),iand(key_in(2,1),act_bitmask(2,1)))), reunion_of_core_inact_bitmask(2,1)) )&
+ popcnt( xor( iand(reunion_of_core_inact_bitmask(2,2), xor(key_in(2,2),iand(key_in(2,2),act_bitmask(2,2)))), reunion_of_core_inact_bitmask(2,2)) )&
+ popcnt( xor( iand(reunion_of_core_inact_bitmask(3,1), xor(key_in(3,1),iand(key_in(3,1),act_bitmask(3,1)))), reunion_of_core_inact_bitmask(3,1)) )&
+ popcnt( xor( iand(reunion_of_core_inact_bitmask(3,2), xor(key_in(3,2),iand(key_in(3,2),act_bitmask(3,2)))), reunion_of_core_inact_bitmask(3,2)) )
else if(N_int == 4)then
number_of_holes = number_of_holes &
+ popcnt( xor( iand(reunion_of_core_inact_bitmask(1,1), xor(key_in(1,1),iand(key_in(1,1),act_bitmask(1,1)))), reunion_of_core_inact_bitmask(1,1)) )&
+ popcnt( xor( iand(reunion_of_core_inact_bitmask(1,2), xor(key_in(1,2),iand(key_in(1,2),act_bitmask(1,2)))), reunion_of_core_inact_bitmask(1,2)) )&
+ popcnt( xor( iand(reunion_of_core_inact_bitmask(2,1), xor(key_in(2,1),iand(key_in(2,1),act_bitmask(2,1)))), reunion_of_core_inact_bitmask(2,1)) )&
+ popcnt( xor( iand(reunion_of_core_inact_bitmask(2,2), xor(key_in(2,2),iand(key_in(2,2),act_bitmask(2,2)))), reunion_of_core_inact_bitmask(2,2)) )&
+ popcnt( xor( iand(reunion_of_core_inact_bitmask(3,1), xor(key_in(3,1),iand(key_in(3,1),act_bitmask(3,1)))), reunion_of_core_inact_bitmask(3,1)) )&
+ popcnt( xor( iand(reunion_of_core_inact_bitmask(3,2), xor(key_in(3,2),iand(key_in(3,2),act_bitmask(3,2)))), reunion_of_core_inact_bitmask(3,2)) )&
+ popcnt( xor( iand(reunion_of_core_inact_bitmask(4,1), xor(key_in(4,1),iand(key_in(4,1),act_bitmask(4,1)))), reunion_of_core_inact_bitmask(4,1)) )&
+ popcnt( xor( iand(reunion_of_core_inact_bitmask(4,2), xor(key_in(4,2),iand(key_in(4,2),act_bitmask(4,2)))), reunion_of_core_inact_bitmask(4,2)) )
else
do i = 1, N_int
number_of_holes = number_of_holes &
+ popcnt( &
xor( &
iand( &
reunion_of_core_inact_bitmask(i,1), &
xor( &
key_in(i,1), & ! MOs of key_in not in the CAS
iand( & ! MOs of key_in in the CAS
key_in(i,1), act_bitmask(i,1) &
) &
) &
), reunion_of_core_inact_bitmask(i,1)) ) &
+ popcnt( xor( iand(reunion_of_core_inact_bitmask(i,2), xor(key_in(i,2),iand(key_in(i,2),act_bitmask(i,2)))), reunion_of_core_inact_bitmask(i,2)) )
enddo
endif
end
integer function number_of_particles(key_in)
BEGIN_DOC
! function that returns the number of particles in the virtual space
END_DOC
implicit none
integer(bit_kind), intent(in) :: key_in(N_int,2)
integer :: i
number_of_particles= 0
if(N_int == 1)then
number_of_particles= number_of_particles &
+ popcnt( iand( xor(key_in(1,1),iand(key_in(1,1),act_bitmask(1,1))), virt_bitmask(1,1) )) &
+ popcnt( iand( xor(key_in(1,2),iand(key_in(1,2),act_bitmask(1,2))), virt_bitmask(1,2) ))
else if(N_int == 2)then
number_of_particles= number_of_particles &
+ popcnt( iand( xor(key_in(1,1),iand(key_in(1,1),act_bitmask(1,1))), virt_bitmask(1,1) ) ) &
+ popcnt( iand( xor(key_in(1,2),iand(key_in(1,2),act_bitmask(1,2))), virt_bitmask(1,2) ) ) &
+ popcnt( iand( xor(key_in(2,1),iand(key_in(2,1),act_bitmask(2,1))), virt_bitmask(2,1) ) ) &
+ popcnt( iand( xor(key_in(2,2),iand(key_in(2,2),act_bitmask(2,2))), virt_bitmask(2,2) ) )
else if(N_int == 3)then
number_of_particles= number_of_particles &
+ popcnt( iand( xor(key_in(1,1),iand(key_in(1,1),act_bitmask(1,1))), virt_bitmask(1,1) )) &
+ popcnt( iand( xor(key_in(1,2),iand(key_in(1,2),act_bitmask(1,2))), virt_bitmask(1,2) )) &
+ popcnt( iand( xor(key_in(2,1),iand(key_in(2,1),act_bitmask(2,1))), virt_bitmask(2,1) )) &
+ popcnt( iand( xor(key_in(2,2),iand(key_in(2,2),act_bitmask(2,2))), virt_bitmask(2,2) )) &
+ popcnt( iand( xor(key_in(3,1),iand(key_in(3,1),act_bitmask(3,1))), virt_bitmask(3,1) )) &
+ popcnt( iand( xor(key_in(3,2),iand(key_in(3,2),act_bitmask(3,2))), virt_bitmask(3,2) ))
else if(N_int == 4)then
number_of_particles= number_of_particles &
+ popcnt( iand( xor(key_in(1,1),iand(key_in(1,1),act_bitmask(1,1))), virt_bitmask(1,1) ) ) &
+ popcnt( iand( xor(key_in(1,2),iand(key_in(1,2),act_bitmask(1,2))), virt_bitmask(1,2) ) ) &
+ popcnt( iand( xor(key_in(2,1),iand(key_in(2,1),act_bitmask(2,1))), virt_bitmask(2,1) ) ) &
+ popcnt( iand( xor(key_in(2,2),iand(key_in(2,2),act_bitmask(2,2))), virt_bitmask(2,2) ) ) &
+ popcnt( iand( xor(key_in(3,1),iand(key_in(3,1),act_bitmask(3,1))), virt_bitmask(3,1) ) ) &
+ popcnt( iand( xor(key_in(3,2),iand(key_in(3,2),act_bitmask(3,2))), virt_bitmask(3,2) ) ) &
+ popcnt( iand( xor(key_in(4,1),iand(key_in(4,1),act_bitmask(4,1))), virt_bitmask(4,1) ) ) &
+ popcnt( iand( xor(key_in(4,2),iand(key_in(4,2),act_bitmask(4,2))), virt_bitmask(4,2) ) )
else
do i = 1, N_int
number_of_particles= number_of_particles &
+ popcnt( iand( xor(key_in(i,1),iand(key_in(i,1),act_bitmask(i,1))), virt_bitmask(i,1) )) &
+ popcnt( iand( xor(key_in(i,2),iand(key_in(i,2),act_bitmask(i,2))), virt_bitmask(i,2) ))
enddo
endif
end
logical function is_a_two_holes_two_particles(key_in)
BEGIN_DOC
! logical function that returns True if the determinant 'key_in'
! belongs to the 2h-2p excitation class of the DDCI space
! this is calculated using the act_bitmask that defines the active
! orbital space, the inact_bitmasl that defines the inactive oribital space
! and the virt_bitmask that defines the virtual orbital space
END_DOC
implicit none
integer(bit_kind), intent(in) :: key_in(N_int,2)
integer :: i,i_diff
integer :: number_of_holes, number_of_particles
is_a_two_holes_two_particles = .False.
if(number_of_holes(key_in) == 2 .and. number_of_particles(key_in) == 2)then
is_a_two_holes_two_particles = .True.
return
endif
i_diff = 0
if(N_int == 1)then
i_diff = i_diff &
+ popcnt( xor( iand(reunion_of_core_inact_bitmask(1,1), xor(key_in(1,1),iand(key_in(1,1),act_bitmask(1,1)))), reunion_of_core_inact_bitmask(1,1)) ) &
+ popcnt( xor( iand(reunion_of_core_inact_bitmask(1,2), xor(key_in(1,2),iand(key_in(1,2),act_bitmask(1,2)))), reunion_of_core_inact_bitmask(1,2)) ) &
+ popcnt( iand( xor(key_in(1,1),iand(key_in(1,1),act_bitmask(1,1))), virt_bitmask(1,1) ) ) &
+ popcnt( iand( xor(key_in(1,2),iand(key_in(1,2),act_bitmask(1,2))), virt_bitmask(1,2) ) )
else if(N_int == 2)then
i_diff = i_diff &
+ popcnt( xor( iand(reunion_of_core_inact_bitmask(1,1), xor(key_in(1,1),iand(key_in(1,1),act_bitmask(1,1)))), reunion_of_core_inact_bitmask(1,1)) ) &
+ popcnt( xor( iand(reunion_of_core_inact_bitmask(1,2), xor(key_in(1,2),iand(key_in(1,2),act_bitmask(1,2)))), reunion_of_core_inact_bitmask(1,2)) ) &
+ popcnt( iand( xor(key_in(1,1),iand(key_in(1,1),act_bitmask(1,1))), virt_bitmask(1,1) ) ) &
+ popcnt( iand( xor(key_in(1,2),iand(key_in(1,2),act_bitmask(1,2))), virt_bitmask(1,2) ) ) &
+ popcnt( xor( iand(reunion_of_core_inact_bitmask(2,1), xor(key_in(2,1),iand(key_in(2,1),act_bitmask(2,1)))), reunion_of_core_inact_bitmask(2,1)) ) &
+ popcnt( xor( iand(reunion_of_core_inact_bitmask(2,2), xor(key_in(2,2),iand(key_in(2,2),act_bitmask(2,2)))), reunion_of_core_inact_bitmask(2,2)) ) &
+ popcnt( iand( xor(key_in(2,1),iand(key_in(2,1),act_bitmask(2,1))), virt_bitmask(2,1) )) &
+ popcnt( iand( xor(key_in(2,2),iand(key_in(2,2),act_bitmask(2,2))), virt_bitmask(2,2) ))
else if(N_int == 3)then
i_diff = i_diff &
+ popcnt( xor( iand(reunion_of_core_inact_bitmask(1,1), xor(key_in(1,1),iand(key_in(1,1),act_bitmask(1,1)))), reunion_of_core_inact_bitmask(1,1)) ) &
+ popcnt( xor( iand(reunion_of_core_inact_bitmask(1,2), xor(key_in(1,2),iand(key_in(1,2),act_bitmask(1,2)))), reunion_of_core_inact_bitmask(1,2)) ) &
+ popcnt( iand( xor(key_in(1,1),iand(key_in(1,1),act_bitmask(1,1))), virt_bitmask(1,1) ) ) &
+ popcnt( iand( xor(key_in(1,2),iand(key_in(1,2),act_bitmask(1,2))), virt_bitmask(1,2) ) ) &
+ popcnt( xor( iand(reunion_of_core_inact_bitmask(2,1), xor(key_in(2,1),iand(key_in(2,1),act_bitmask(2,1)))), reunion_of_core_inact_bitmask(2,1)) ) &
+ popcnt( xor( iand(reunion_of_core_inact_bitmask(2,2), xor(key_in(2,2),iand(key_in(2,2),act_bitmask(2,2)))), reunion_of_core_inact_bitmask(2,2)) ) &
+ popcnt( iand( xor(key_in(2,1),iand(key_in(2,1),act_bitmask(2,1))), virt_bitmask(2,1) ) ) &
+ popcnt( iand( xor(key_in(2,2),iand(key_in(2,2),act_bitmask(2,2))), virt_bitmask(2,2) ) ) &
+ popcnt( xor( iand(reunion_of_core_inact_bitmask(3,1), xor(key_in(3,1),iand(key_in(3,1),act_bitmask(3,1)))), reunion_of_core_inact_bitmask(3,1)) ) &
+ popcnt( xor( iand(reunion_of_core_inact_bitmask(3,2), xor(key_in(3,2),iand(key_in(3,2),act_bitmask(3,2)))), reunion_of_core_inact_bitmask(3,2)) ) &
+ popcnt( iand( xor(key_in(3,1),iand(key_in(3,1),act_bitmask(3,1))), virt_bitmask(3,1) ) ) &
+ popcnt( iand( xor(key_in(3,2),iand(key_in(3,2),act_bitmask(3,2))), virt_bitmask(3,2) ) )
else if(N_int == 4)then
i_diff = i_diff &
+ popcnt( xor( iand(reunion_of_core_inact_bitmask(1,1), xor(key_in(1,1),iand(key_in(1,1),act_bitmask(1,1)))), reunion_of_core_inact_bitmask(1,1)) ) &
+ popcnt( xor( iand(reunion_of_core_inact_bitmask(1,2), xor(key_in(1,2),iand(key_in(1,2),act_bitmask(1,2)))), reunion_of_core_inact_bitmask(1,2)) ) &
+ popcnt( iand( xor(key_in(1,1),iand(key_in(1,1),act_bitmask(1,1))), virt_bitmask(1,1) ) ) &
+ popcnt( iand( xor(key_in(1,2),iand(key_in(1,2),act_bitmask(1,2))), virt_bitmask(1,2) ) ) &
+ popcnt( xor( iand(reunion_of_core_inact_bitmask(2,1), xor(key_in(2,1),iand(key_in(2,1),act_bitmask(2,1)))), reunion_of_core_inact_bitmask(2,1)) ) &
+ popcnt( xor( iand(reunion_of_core_inact_bitmask(2,2), xor(key_in(2,2),iand(key_in(2,2),act_bitmask(2,2)))), reunion_of_core_inact_bitmask(2,2)) ) &
+ popcnt( iand( xor(key_in(2,1),iand(key_in(2,1),act_bitmask(2,1))), virt_bitmask(2,1) ) ) &
+ popcnt( iand( xor(key_in(2,2),iand(key_in(2,2),act_bitmask(2,2))), virt_bitmask(2,2) ) ) &
+ popcnt( xor( iand(reunion_of_core_inact_bitmask(3,1), xor(key_in(3,1),iand(key_in(3,1),act_bitmask(3,1)))), reunion_of_core_inact_bitmask(3,1)) ) &
+ popcnt( xor( iand(reunion_of_core_inact_bitmask(3,2), xor(key_in(3,2),iand(key_in(3,2),act_bitmask(3,2)))), reunion_of_core_inact_bitmask(3,2)) ) &
+ popcnt( iand( xor(key_in(3,1),iand(key_in(3,1),act_bitmask(3,1))), virt_bitmask(3,1) ) ) &
+ popcnt( iand( xor(key_in(4,2),iand(key_in(3,2),act_bitmask(3,2))), virt_bitmask(3,2) ) ) &
+ popcnt( xor( iand(reunion_of_core_inact_bitmask(4,1), xor(key_in(4,1),iand(key_in(4,1),act_bitmask(4,1)))), reunion_of_core_inact_bitmask(4,1)) ) &
+ popcnt( xor( iand(reunion_of_core_inact_bitmask(4,2), xor(key_in(4,2),iand(key_in(4,2),act_bitmask(4,2)))), reunion_of_core_inact_bitmask(4,2)) ) &
+ popcnt( iand( xor(key_in(4,1),iand(key_in(4,1),act_bitmask(4,1))), virt_bitmask(4,1) ) ) &
+ popcnt( iand( xor(key_in(4,2),iand(key_in(4,2),act_bitmask(4,2))), virt_bitmask(4,2) ) )
else
do i = 1, N_int
i_diff = i_diff &
+ popcnt( xor( iand(reunion_of_core_inact_bitmask(i,1), xor(key_in(i,1),iand(key_in(i,1),act_bitmask(i,1)))), reunion_of_core_inact_bitmask(i,1)) ) &
+ popcnt( xor( iand(reunion_of_core_inact_bitmask(i,2), xor(key_in(i,2),iand(key_in(i,2),act_bitmask(i,2)))), reunion_of_core_inact_bitmask(i,2)) ) &
+ popcnt( iand( xor(key_in(i,1),iand(key_in(i,1),act_bitmask(i,1))), virt_bitmask(i,1) )) &
+ popcnt( iand( xor(key_in(i,2),iand(key_in(i,2),act_bitmask(i,2))), virt_bitmask(i,2) ))
enddo
endif
is_a_two_holes_two_particles = (i_diff >3)
end
integer function number_of_holes_verbose(key_in)
BEGIN_DOC
! function that returns the number of holes in the inact space
END_DOC
implicit none
integer(bit_kind), intent(in) :: key_in(N_int,2)
integer :: i
integer(bit_kind) :: key_tmp(N_int,2)
print*,'HOLES '
print*,'jey_in = '
call debug_det(key_in,N_int)
number_of_holes_verbose = 0
key_tmp(1,1) = xor(key_in(1,1),iand(key_in(1,1),act_bitmask(1,1)))
key_tmp(1,2) = xor(key_in(1,2),iand(key_in(1,2),act_bitmask(1,1)))
call debug_det(key_tmp,N_int)
key_tmp(1,1) = iand(key_tmp(1,1),reunion_of_core_inact_bitmask(1,1))
key_tmp(1,2) = iand(key_tmp(1,2),reunion_of_core_inact_bitmask(1,2))
call debug_det(key_tmp,N_int)
key_tmp(1,1) = xor(key_tmp(1,1),reunion_of_core_inact_bitmask(1,1))
key_tmp(1,2) = xor(key_tmp(1,2),reunion_of_core_inact_bitmask(1,2))
call debug_det(key_tmp,N_int)
! number_of_holes_verbose = number_of_holes_verbose + popcnt(key_tmp(1,1)) &
! + popcnt(key_tmp(1,2))
number_of_holes_verbose = number_of_holes_verbose &
+ popcnt( xor( iand(reunion_of_core_inact_bitmask(1,1), xor(key_in(1,1),iand(key_in(1,1),act_bitmask(1,1)))), reunion_of_core_inact_bitmask(1,1)) )&
+ popcnt( xor( iand(reunion_of_core_inact_bitmask(1,2), xor(key_in(1,2),iand(key_in(1,2),act_bitmask(1,2)))), reunion_of_core_inact_bitmask(1,2)) )
print*,'----------------------'
end
integer function number_of_particles_verbose(key_in)
BEGIN_DOC
! function that returns the number of particles in the inact space
END_DOC
implicit none
integer(bit_kind), intent(in) :: key_in(N_int,2)
integer :: i
integer(bit_kind) :: key_tmp(N_int,2)
print*,'PARTICLES '
print*,'jey_in = '
call debug_det(key_in,N_int)
number_of_particles_verbose = 0
key_tmp(1,1) = xor(key_in(1,2),iand(key_in(1,2),act_bitmask(1,1)))
key_tmp(1,2) = xor(key_in(1,2),iand(key_in(1,2),act_bitmask(1,1)))
call debug_det(key_tmp,N_int)
key_tmp(1,1) = iand(key_tmp(1,2),virt_bitmask(1,2))
key_tmp(1,2) = iand(key_tmp(1,2),virt_bitmask(1,2))
call debug_det(key_tmp,N_int)
key_tmp(1,1) = iand(key_tmp(1,1),virt_bitmask(1,1))
key_tmp(1,2) = iand(key_tmp(1,2),virt_bitmask(1,2))
call debug_det(key_tmp,N_int)
! number_of_particles_verbose = number_of_particles_verbose + popcnt(key_tmp(1,1)) &
! + popcnt(key_tmp(1,2))
number_of_particles_verbose = number_of_particles_verbose &
+ popcnt( iand( iand( xor(key_in(1,1),iand(key_in(1,1),act_bitmask(1,1))), virt_bitmask(1,1) ), virt_bitmask(1,1)) ) &
+ popcnt( iand( iand( xor(key_in(1,2),iand(key_in(1,2),act_bitmask(1,2))), virt_bitmask(1,2) ), virt_bitmask(1,2)) )
end
logical function is_a_1h1p(key_in)
implicit none
integer(bit_kind), intent(in) :: key_in(N_int,2)
integer :: number_of_particles, number_of_holes
is_a_1h1p = (number_of_holes(key_in) == 1) .and. (number_of_particles(key_in) == 1)
end
logical function is_a_1h2p(key_in)
implicit none
integer(bit_kind), intent(in) :: key_in(N_int,2)
integer :: number_of_particles, number_of_holes
is_a_1h2p = (number_of_holes(key_in) == 1) .and. (number_of_particles(key_in) == 2)
end
logical function is_a_2h1p(key_in)
implicit none
integer(bit_kind), intent(in) :: key_in(N_int,2)
integer :: number_of_particles, number_of_holes
is_a_2h1p = (number_of_holes(key_in) == 2) .and. (number_of_particles(key_in) == 1)
end
logical function is_a_1h(key_in)
implicit none
integer(bit_kind), intent(in) :: key_in(N_int,2)
integer :: number_of_particles, number_of_holes
is_a_1h = (number_of_holes(key_in) == 1) .and. (number_of_particles(key_in) == 0)
end
logical function is_a_1p(key_in)
implicit none
integer(bit_kind), intent(in) :: key_in(N_int,2)
integer :: number_of_particles, number_of_holes
is_a_1p = (number_of_holes(key_in) == 0) .and. (number_of_particles(key_in) == 1)
end
logical function is_a_2p(key_in)
implicit none
integer(bit_kind), intent(in) :: key_in(N_int,2)
integer :: number_of_particles, number_of_holes
is_a_2p = (number_of_holes(key_in) == 0) .and. (number_of_particles(key_in) == 2)
end
logical function is_a_2h(key_in)
implicit none
integer(bit_kind), intent(in) :: key_in(N_int,2)
integer :: number_of_particles, number_of_holes
is_a_2h = (number_of_holes(key_in) == 2) .and. (number_of_particles(key_in) == 0)
end
logical function is_i_in_virtual(i)
implicit none
integer,intent(in) :: i
integer(bit_kind) :: key(N_int)
integer :: k,j
integer :: accu
is_i_in_virtual = .False.
key= 0_bit_kind
k = shiftr(i-1,bit_kind_shift)+1
j = i-shiftl(k-1,bit_kind_shift)-1
key(k) = ibset(key(k),j)
accu = 0
do k = 1, N_int
accu += popcnt(iand(key(k),virt_bitmask(k,1)))
enddo
if(accu .ne. 0)then
is_i_in_virtual = .True.
endif
end