O. Shpotyuk, R. Golovchak, V. Boyko, and S. Kozyukhin.
Physica Status Solidi C, vol. 7, No. 3–4, 2010, p. 921– 924.
The developed cluster modeling approach based on ab-initio calculations with RHF/6-311G* basis set testifies absence of intermediate optimally-constrained phase in binary GexSe100-x system within 20 ≤ x < 26 domain. It is shown, that character “outrigger raft” carcass is conserved for all glass compositions within expected reversibility window. Thus, the structure of binary GexSe100-x glasses can be described in terms of “chains crossing” model in case of x < 12, mixed “chains crossing” and “outrigger raft” models in case of 12 ≤ x < 20 and modified “outrigger raft” model in case of x ≥ 20. The expected reversibility window in binary GexSe100-x glasses is shown to be only quasi-adaptive phase, based on “outrigger raft” structural motive with two edge- and four corner-sharing tetrahedra interconnected by optimally-constrained Ge-Se-Se-Ge bridges with extra Se atoms in ring-like configurations replaced Se-Se dimers. The results of quantum mechanics modeling are confirmed well by high-resolution X-ray photoelectron spectroscopy measurements in this system.