The article discusses the use of mathematical modeling to obtain properties of silicon. The nonequilibrium heating of semiconductor proceeds with a large separation of temperatures of the current carriers from the lattice, therefore, in the problems of laser action a silicon target can be regarded as an object consisting of two interacting subsystems, electron and phonon subsystems. At the same time, for each of subsystems it is necessary to determine thermophysical, optical and thermodynamic characteristics that vary over a wide temperature range. To determine the properties of the electronic subsystem a continual approach was used, and for the phonon subsystem a molecular-dynamic approach was used. Such properties of the electron Fermi gas as electron concentration Ne(T), holes concentration Nh(T), Fermi energy EF(T), band gap Eg(T,N), carrier mobility μ(T,N), electrical conductivity σ(T,N) are determined within the framework of quantum statistics in an arbitrary degeneracy range when the temperature varies from 300K to 2000K. The most important characteristics of the phonon subsystem such as the pressure dependences of the melting temperature of silicon Tm(P) and the heat of melting Lm(P), and the temperature dependence of the heat of evaporation Lv(T) were determined. The results are compared with the experimental data.