Cluster expansion of the wavefunction. Pseudo‐orbital theory based on the SAC expansion and its application to the spin density of open‐shell systems

摘要: We have studied the pseudo‐orbital theory, which is based on symmetry‐adapted‐cluster (SAC) expansion of an exact wavefunction proposed previously, in comparison with conventional open‐shell orbital theories, and applied it to calculations spin densities first‐row atoms, Li(2S), Li(2P), Be+(2S), B2+(2S), B(2P), C(3P), N(4S), O(3P), F(2P). started from RHF reference considered mainly spin‐polarization excitation operator its self‐consistency effect. This theory corresponds extension UHF spin‐extended HF (SEHF) yet free theoretical defects found previously for these theories. The relative magnitudes calculated are predicted be order or SEHF, present, first‐order (FO) CI decreasing order. sequence has been confirmed atoms. For three‐electron atoms present give...