Calculation of soft atomic potentials formed by three-center bonds in germanosilicate glass

Abstract

Properties of the neutral, singly and doubly negatively charged GeOGe linkages and of the neutral GeOGe linkage stretched from 0.34 to 0.46 nm in vitreous silicon dioxide are studied in an isolated molecular cluster model with quantum-chemical methods. The soft atomic potential caused by the formation of three-center bonds between atoms of the linkage is found to arise in the neutral GeOGe linkage stretched to ∼ 0.40 nm. No soft potential is formed in the SiOGe linkage and in the singly negatively charged GeOGe linkage. Capture of a pair of electrons in the GeOGe linkage results in softening of the atomic potential, the soft potential and the three-center bond being formed in the linkage stretched even to 0.38 nm. Results of calculations of electronic structures of the three-center bonds and vibrational properties of the stretched neutral and charged GeOGe linkages are discussed.