LCAO Calculations of Perfect-crystal Properties

In the next three chapters we illustrate the possibiUties of LCAO methods in the calculations of different crystaUine-sohd properties. 

We do not discuss here the electron-phonon and isotope effects on the optical spectra of sohds. In [564, 565] these effects were studied in the framework of the tight-binding (TB) LCAO approach for several semiconductors with diamond and zincblende structure. The results reproduce the overall trend of the available experimental data for the bandgap as a function of temperature, as well as give correctly the mass dependence of the bandgap. 

The TB approach represents a conceptual bridge between ab-initio simulations and model-potential ones. In particular, the coupling of TB with the molecular dynamics (MD) generates the TBMD method as a valuable tool for atomic-scale materials modeling [566]. A description of the TB method can be found, for example, in [6,567]. 

In this chapter the perfect-crystal properties are considered the analysis of chemical bonding on the basis of population analysis, the one-electron properties and prop -erties, defined by the total energy and its derivatives and the magnetic ordering in crystals. 

In Chap. 10 we discuss the models of crystals with point defects and calculation of their properties by LCAO methods. 

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