RESIDUAL ENTROPY OF GLASS CONNECTED WITH ISOMETRY OF THE SUBSYSTEM OF 3-CENTER BONDS

The statistical approach after Pauling and Tolman is developed considering N, the number of degenerated structural states responsible for the residual entropy of glass S(o), as the number of isomers of three-centre bonds (TCB) coexisting with covalent bonds (CB) in glass network. Various types of TCB isomers are possible: structural (tautomers), optical (enantiomers), and topological, which are frozen below the glass transition temperature ensuring S(o) This model is in fact a two-structural model of glass since it distinguishes one subsystem consisting of structural polyhedra based on rigid CB and another subsystem of non-rigid TCB, and hence S(o) contains one part due to disorder in the CB subsystem and another part due to isomery in the TCB one. These parts are determined numerically for Se and SiO2 as typical exemplars. The given interpretation of S(o) is compared with others including Angell`s configuron model.