The probabilities of radiation-induced
charged coordination defects in the form of dipole-type valence alteration pairs were estimated for glass-forming chalcogenide networks built of edge-shared GeS
4/2 tetrahedrons, AsS
3/2 trigonal pyramids and S
n chains. Geometrical optimization and single-point energy calculation was performed for selected atomic
clusters utilizing
ab-
initio quantum-chemical modeling with CINCA (cation-interlinking network cluster approach) algorithm, the computed atomic configurations being compared by corresponding cluster-forming energies accepting inner distortions in coordination polyhedrons with miscoordinated atoms.
It was concluded such dipole-type defective configurations could be unlikely realized in Ge–S and As–S glasses, because of unrealistically high energetic gains needed to accommodate lateral and angular distortions connected with three-fold closed rings and homopolar S–S bonds. Defect formation energy was minimal in chain-like glassy structures built by only S atoms, but corresponding energetic barrier left still high to activate such transformations under thermodynamically stabilized conditions.
