Type | Intent | Optional | Attributes | Name | ||
---|---|---|---|---|---|---|
integer, | intent(in) | :: | n_elecs | |||
integer, | intent(in) | :: | n_orbs | |||
integer, | intent(in) | :: | ic |
function calc_n_parallel_excitations(n_elecs, n_orbs, ic) result(n_parallel)
! this function determines the number of parallel spin excitaiton
! with each electrons having the same spin for a given excitation
! level and number of electrons and available orbitals for this spin
integer, intent(in) :: n_elecs, n_orbs, ic
integer :: n_parallel
n_parallel = int(choose_i64(n_elecs, ic) * choose_i64(n_orbs - n_elecs, ic))
end function calc_n_parallel_excitations