Simulation of spatial correlations of impurity ions in solids using configurational entropy and the hard-sphere model

Based on the hard-sphere model, the spatial correlations are considered in a system of impurities with variable valency. In a zeroth approximation, the configurational entropy of the spatially correlated system of impurity ions is identified with the configurational entropy of a system of hard spheres. The electron mobility limited by scattering on the correlated system of impurity ions at finite temperatures is found. The theory developed explains experimentally observed anomalies of the carrier mobility in an iron-doped HgSe gapless semiconductor.