Energy Band and Lattice Structures of Trigonal Se and Te in the Vector Charge Density Wave Model : Condensed Matter and Statistical Physics

概要

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The energy band and lattice structures of trigonal Se and Te are calculated by the vector charge density wave (VCDW) model. A little simplified VCDW model is formulated using the CNDO-UHF approximation. The VCDW model with a suitable parametrization is shown to explain the geometry, XPS and optical gap data. The Fermi surface of the cubic p band is shown to have a nesting structure responsible to produce the VCDW. The band dispersion of trigonal Se and Te is mainly determined by the dispersion of the cubic p bands that correspond to the prototype lattice structure of the trigonal crystal. The VCDW produces gaps and splits the metallic cubic p bands into three subbands. The lattice distortion by the electron-lattice coupling, the nearest neighbor exchange interaction and the intraatomic Coulomb repulsion additively contribute to the gaps. The lattice distortion is proportional to the bond order modulation of the VCDW. The contribution of the nearest neighbor exchange interaction to the gaps is also proportional to it, while that of the intraatomic Coulomb repulsion is proportional to the p electron density modulation of the VCDW.
理論物理学刊行会の論文
1988-03-25