add_semistochastic_state Subroutine

    subroutine add_semistochastic_state(ilut_list, list_size, ssht, ilut)
        use FciMCData, only: ll_node, MaxWalkersPart
        use hash, only: hash_table_lookup, add_hash_table_entry
        use bit_reps, only: encode_sign
        implicit none
        type(ll_node), pointer, intent(inout) :: ssht(:)
        integer(n_int), intent(inout) :: ilut_list(0:, 1:)
        integer, intent(inout) :: list_size
        integer(n_int), intent(in) :: ilut(0:nifTot)
        integer :: index, hash_val, nI(nel)
        logical :: tSuccess
        real(dp) :: new_sgn(lenof_sign), old_sgn(lenof_sign)
        character(*), parameter :: this_routine = "add_semistochastic_state"

        call decode_bit_det(nI, ilut)
        call hash_table_lookup(nI, ilut, nifd, ssht, ilut_list, index, hash_val, tSuccess)
        ! If it is already in corespace, we check which population is higher
        if (tSuccess) then
            call extract_sign(ilut_list(:, index), old_sgn)
            call extract_sign(ilut, new_sgn)
            if (sum(abs(new_sgn)) > sum(abs(old_sgn))) call encode_sign(ilut_list(:, index), new_sgn)
        else
            if (list_size > MaxWalkersPart) call stop_all(this_routine, &
                                                          "Out of memory for corespace construction.")
            list_size = list_size + 1
            ilut_list(:, list_size) = ilut
            call add_hash_table_entry(ssht, list_size, hash_val)
        end if
    end subroutine add_semistochastic_state