Electronic calculations for molecules

This section will contain less analytical and more straightforward presentation of current experimental and theoretical results and ideas. The field is developing extremely rapidly and fairly little has been done so far in terms of quantitative calculations on real systems. Most of the theoretical investigations have been in the form of one-electron calculations for molecules and clusters, or many-body calculations on model systems. We shall discuss a number of cases where hole spectra in extended systems are strongly influenced or, in certain regions, even dominated by atomic-like, local excitations, with the particular aim of presenting an overview of unifying aspects. 

All these qualitative changes and trends can be inferred from results of atomic calculations obtained at the beginning of the seventies of the last century, but it remained to obtain more quantitative results. At that time all electron calculations for molecules involving heavy atoms using relativistic four component molecular orbitals were practically intractable even at the simple Hartree-Fock level. Therefore, early relativistic quantum chemistry emerged from the following various approximations ... 

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See also in sourсe #XX -- [ , ]

See also in sourсe #XX -- [ ]

See also in sourсe #XX -- [ , ]

See also in sourсe #XX -- [ , ]

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