Orbital language spin-orbitals

The vinyl H2C=CH radical can be produced by cleavage of a C-H bond in ethene, and has been studied in the gas phase. The unpaired electron clearly occupies a carbon sp hybrid orbital, to lapse into the language of descriptive organic chemistry, but there are regions of space where the, 6-spin electrons have... 

At the same time, Meissner, Kucharski and others [56,57] developed the quadratic MR CCSD method in a spin-orbital form which does not exploit the BCH formula. The unknown cluster amplitudes are calculated from the so-called generalized Bloch equation [45-47,49,64,65] (or in our language the Bloch equation in the Rayleigh-Schrodinger form)... 

Furthennore, the VB orbitals, and spin couplings, of a C-H bond in say propane and butane" are very similar, in contrast to the vastly different MO descriptions of the two systems. The VB picture is thus much closer to the traditional descriptive language, with molecules composed of functional groups. The widespread availability of programs for performing TASSCF calculations, and the fact that CASSCF calculations are-... 

Silverstone and Sinanoglu [77] wrote the cluster expansion of fhe nonrela-f ivisfic N-elecf ron eigenfunction in terms of a zero-order reference wavefunc-fion fhaf is multicmfigurational, in accordance wifh the earlier suggestion of Wafson [31] and the study of H-ND in Be [75, 76]. In their formalism, the one-, two-, three-, etc. correlation functions (i.e., the virtual electron-excitations in the language of Cl) are linked fo spin orbitals from an extended zero-order set of occupied and unoccupied spin orbitals. This set was named the Hartree-Fock sea (H-F sea). Optimally, the H-F sea spin orbitals are supposed to be computed self-consistently. 

Each electron is then assigned an orbital determined by the electric field of the nuclear system and all the other electrons, and each orbital can be occupied by two electrons having opposite spins. The final wave function of the molecule is then taken as the product of these separate electron molecular orbitals. In the language of the organic chemist, this amounts to the obliteration of any distinctive... 

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