pyscfad.cc.rccsd.mo_energy_denominators#

pyscfad.cc.rccsd.mo_energy_denominators(mo_e_o, mo_e_v, mo_mask=None)[source]#

Orbital-energy denominators \(\Delta_i^a\) and \(\Delta_{ij}^{ab}\).

Parameters:

  • mo_e_o (Array) – Occupied orbital energies.

  • mo_e_v (Array) – Virtual orbital energies.

  • mo_mask (Array | None) – Mask flagging the real (non-padding) MOs, as returned by mo_mask(). None when every MO is real.

Return type:

tuple[Array, Array]

Notes

A padding MO enters no integral, so its diagonal Fock element, and hence its orbital energy, is zero up to round-off. eia therefore vanishes for a pair of padding orbitals – where the numerator vanishes as well – and the denominator is replaced by one there to keep the ratio, and its derivative, finite.