Investigation of the structural units of germanium sulfide and selenide by quantum chemical methods

This article deals with the modeling of the structural units (clusters) of germanium sulfide and germanium selenide glasses by quantum chemical (ab initio Hartree-Fock) methods. Clusters of different sizes were investigated. Geometric parameters and vibrational frequencies of these structural units were calculated. The quantum chemical calculations were followed by normal coordinate analysis. Based on the yielded results, the vibrational spectra of the clusters were simulated. The results for germanium sulfide and germanium selenide were compared. It was concluded that in the spectral regions where germanium sulfide is not applicable for fiber optics, germanium selenide or different germanium sulfide-selenides are suitable to replace it. (C) 2001 John Wiley & Sons, Inc.