Quasi-relativistic approximation in the SCF-MO-LCAO method

✍ Scribed by I. B. Bersuker; S. S. Budnikov; B. A. Leizerov

• Publisher: John Wiley and Sons
• Year: 1972
• Tongue: English
• Weight: 414 KB
• Volume: 6
• Category: Article
• ISSN: 0020-7608
• DOI: 10.1002/qua.560060505

✦ Synopsis

Abstract

A quasi‐relativistic approach to the MO‐LCAO method is formulated taking into account the relativistic effects with an accuracy up to (v/c)^2^ terms, the relativistic part of the electronic interaction in the Hamiltonian being neglected. In the framework of this approximation a set of SCF equations of the Roothaan form is derived; here only the relativistic analogue to the closed shell systems with one‐determinant wave functions is considered. In so doing three types of relativistic corrections arise which are quite similar to those of the Pauli equation for one‐electron atoms. The new matrix elements appearing due to these corrections can be reduced to some common integrals, which have to be calculated with relativistic radial atomic functions. The method allows a semi‐empirical approach to the problem and does not require the Dirac four‐component atomic functions (unknown in the most cases), thus making possible approximate quasi‐relativistic electronic structure calculations of heavy‐atom compounds.