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Lattice-gas model for alkali-metal fullerides: face-centered-cubic structure

Laszlo Udvardi·Gyorgy Szabo
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Abstract

A lattice-gas model is suggested for describing the ordering phenomena in alkali-metal fullerides of face-centered-cubic structure assuming the electric charge of alkali ions residing in either octahedral or tetrahedral interstitial sites is completely screened by the first-neighbor C_60 molecules. This approximation allows us to derive an effective ion-ion interaction. The van der Waals interaction between the ion and C_60 molecule is characterized by introducing an additional energy at the tetrahedral sites. This model is investigated by using a three-sublattice mean-field approximation and a simple cluster-variation method. The analysis shows a large variety of phase diagrams when changing the site energy parameter.

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Laszlo Udvardi, Gyorgy Szabo. 1995-12-01. Lattice-gas model for alkali-metal fullerides: face-centered-cubic structure. https://doi.org/10.1088/0953-8984%2F8%2F50%2F022

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