TABLE XII.
Correlation contributions due to the 2s orbitals at the SDT and SDTQ levels in the CAS(2,2) function, i.e., the energy differences ΔE (2,2) =E [CAS(2,2)*] −E [CAS(2,2)] =E (excluding excitations from the 2s orbitals) −E (including excitations from the 2s orbitals), in mh.
| Geometry | ||||||
|---|---|---|---|---|---|---|
| Excitation level | OM | TSa | XM | CIa | RM | |
| Ref. + SDT | 11A1 | 246.25 | 239.53 | 239.49 | 234.84 | 245.77 |
| 21A1 | 231.81 | 230.06 | 230.14 | 225.78 | 236.43 | |
| Ref. + SDTQ | 11A1 | 289.39 | 283.49 (283.09) | 283.81 | 280.28 (279.87) | 288.93 |
| 21A1 | 286.43 | 279.35 (279.87) | 276.31 | 272.64 (273.83) | 276.14 | |
a
All SDTQ energies without parentheses were obtained by CEEIS extrapolation. The energy differences in parentheses were obtained using exact CAS(2,2)* energies.