GetH0Element4 Function

    HElement_t(dp) function GetH0Element4(nI, HFDet)
        ! Returns the matrix element of the unperturbed Hamiltonian,
        ! which is just the sum of the eigenvalues of the occupied
        ! orbitals and the core energy.
        ! HOWEVER, this routine is *SLOWER* than the GetH0Element3
        ! routine, and should only be used if you require this
        ! without reference to the fock eigenvalues.
        ! This is calculated by subtracting the required two electron terms
        ! from the diagonal matrix elements.
        integer, intent(in) :: nI(NEl), HFDet(NEl)
        HElement_t(dp) :: hel

        hel = SumFock(nI, HFDet)
        GetH0Element4 = hel + ECore

    end function GetH0Element4