Interpretation of Moessbauer parameters on the basis of molecular orbital theory

This is a lecture note given by Prof. Alfled Trautwein at the Research Reactor Institute of Kyoto University in March, 1976. Contents are the energy expression for a closed-shell configuration, the concept of self-consistency, the limitations of a free-ion or crystal field approach, molecular cluster approach, electron density, quadrupole splitting, magnetic hyperfine interaction and conclusion. The energy expression for a 2n-electron system was introduced from the Schroedinger equation. The control mathematical problem associated with finding a stationary value for the expectation value is the determination of self-consistent or Hartree-Fock MO's wave function. In order to obtain self-consistency, the equations have to be solved by an interactive procedure. As a concluding remarks, the author says that it is able to compare calculated results with experimental ones from the study of Moessbauer parameters on the basis of molecular cluster calculations. It is found that effects generally referred to as ''covalent effects'' can play a significant role for the interpretation of electric and magnetic hyperfine interaction. (Kato, T.)