Abstract: | The problem of calculating the electronic energy spectra of mixed-valence clusters with one “extra” electron (dn-dn...dn+1) or hole (dn+1-dn+1...dn) delocalized in the paramagnetic cores of transition metals is solved. Unlike the available particular solutions, which are
restricted to small numbers of ions and electrons, the solution proposed in this work is general and is suitable for many-electron
systems of arbitrary numbers of nuclei and arbitrary symmetries. The new microscopic approach to the double exchange problem
is based on the combination of the sequential (“chain”) scheme of spin coupling and angular momentum method. In terms of this
approach, an analytical dependence of the matrix elements of the double exchange, Heisenberg exchange, and vibronic interaction
on all spin quantum numbers is obtained. The final equations contain only the 6j symbols and are free of the higher-order
nj symbols, which obstructed the solution of the double exchange problem in previous works.
Valencia University, Spain. Bordeaux University, France. Moldova State University. Institute of Chemistry, Academy of Sciences,
Moldova Republic. Translated fromZhurnal Strukturnoi Khimii, Vol. 37, No. 5, pp. 805–815, September–October, 1996.
Translated by I. Izvekova |