SEMICLASSICAL APPROXIMATION IN THE MAGNETIC PROBLEM OF EXCHANGE-COUPLED MIXED-VALENCE CLUSTERS

The frameworks of the applicability of the semiclassical adiabatic approach suggested by Borras-Almenar, Coronado and Tsukerblat to the magnetic problem of mixed valence clusters are considered in a model taking into account magnetic exchange, double exchange and vibronic interaction. The results for the quantum-mechanical and semiclassical calculation of the temperature-variable magnetic moments are compared with those within the scope of the semiclassical approximation for the dimeric d(1)-d(2) clusters and trimeric d(1)-d(1)-d(2) systems with partial delocalization over a pair of ions. The semiclassical approach describes with high accuracy the temperature dependencies of the magnetic moments. Cases of the inapplicability of the semiclassical approach are pointed out.