The mathematical model and method for the thermal expansion coefficient of solids study using the structural units method is presented: theoretical and experimental approach based on the use of potentials of interatomic interaction and micro-and macrostructural data: atomic or molecular configuration of the structural unit, known parameters ( D , ± , r ) of the modified Morse potential for metals (Al, Cu, Fe) and physical parameters of the whole object. This method involves the use of

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... al modeling in conjunction with experimental data: in the process of model equations computing using empirical data. Purposed method allows theoretical calculation of the microstructural dynamic linear (CLTE) and volumetric coefficient of thermal expansion taking into account the pro-cess time in the range between structural transitions in a wide temperature range with a known structural unit configuration, taking into account the energy characteristics of the polyatomic interaction of the microstructure. Calculations of the theoretical dynamic microstructural coefficient of linear expansion for Al, Cu and Fe in a wide temperature range (0-1 500 С) according to known initial parameters of the interatomic potential are obtained and compared to experimental data of macrostructural coefficient of thermal expansion. The graphs of microstructural coefficient of thermal expansion values was obtained with the help of computer modeling compared to macrostructural coefficient of thermal expansion varies in range 5-12%. Presented method can also be used in the case of alloys and solid solutions with a known microstructural configuration necessary for calculating the parameters of structural unit. The use of this model for calculating the parameters of anisotropic materials is possible only with regard to the use of the experimental structural unit density dependence on temperature, allows not only to obtain adequate results of calculations for the processes occurring in a particular material at the micro level, but also to understand the physical basis of these processes.