# get_helement_k_space_hub_general Function

## public function get_helement_k_space_hub_general(nI, nJ, ic_ret) result(hel)

### Arguments

Type IntentOptional Attributes Name
integer, intent(in) :: nI(nel)
integer, intent(in) :: nJ(nel)
integer, intent(inout), optional :: ic_ret

## Source Code

    function get_helement_k_space_hub_general(nI, nJ, ic_ret) result(hel)
integer, intent(in) :: nI(nel), nJ(nel)
integer, intent(inout), optional :: ic_ret
HElement_t(dp) :: hel
integer :: ic, ex(2, 3), ex_2(2, 2)
logical :: tpar
integer(n_int) :: ilutI(0:NIfTot), ilutJ(0:niftot)

!todo: if 2-body-transcorrelation, we can have triple excitations now..
! fix that here.. (and also in a lot of other parts in the code..)
if (present(ic_ret)) then
if (ic_ret == 0) then
hel = get_diag_helement_k_sp_hub(nI)

else if (ic_ret == 2) then
ex_2(1, 1) = 2

call GetExcitation(nI, nJ, nel, ex_2, tpar)
hel = get_offdiag_helement_k_sp_hub(nI, ex_2, tpar)

else if (ic_ret == 3 .and. t_trans_corr_2body) then
ex(1, 1) = 3
call GetExcitation(nI, nJ, nel, ex, tpar)
hel = get_3_body_helement_ks_hub(ex, tpar)

else if (ic_ret == -1) then
call EncodeBitDet(nI, ilutI)
call EncodeBitDet(nJ, ilutJ)

ic_ret = FindBitExcitLevel(ilutI, ilutJ)

if (ic_ret == 0) then
hel = get_diag_helement_k_sp_hub(nI)

else if (ic_ret == 2) then
ex_2(1, 1) = 2
call GetBitExcitation(ilutI, ilutJ, ex_2, tpar)
hel = get_offdiag_helement_k_sp_hub(nI, ex_2, tpar)

else if (ic_ret == 3 .and. t_trans_corr_2body) then
ex(1, 1) = 3
call GetBitExcitation(ilutI, ilutJ, ex, tpar)

hel = get_3_body_helement_ks_hub(ex, tpar)

else
hel = h_cast(0.0_dp)
end if
else
hel = h_cast(0.0_dp)
end if
else
call EncodeBitDet(nI, ilutI)
call EncodeBitDet(nJ, ilutJ)

ic = FindBitExcitLevel(ilutI, ilutJ)

if (ic == 0) then
hel = get_diag_helement_k_sp_hub(nI)
else if (ic == 2) then
ex_2(1, 1) = 2

call GetBitExcitation(ilutI, ilutJ, ex_2, tpar)
hel = get_offdiag_helement_k_sp_hub(nI, ex_2, tpar)

else if (ic == 3 .and. t_trans_corr_2body) then
ex(1, 1) = 3
call GetBitExcitation(ilutI, ilutJ, ex, tpar)

hel = get_3_body_helement_ks_hub(ex, tpar)

else
hel = h_cast(0.0_dp)
end if
end if

end function get_helement_k_space_hub_general