Functional form of the repulsive potential in the high pressure region

The present work is devoted to the analysis of the functional form of the repulsive potential in the framework of soft-sphere model. We used two different approaches which were based on the treatment of an equation of state and spectra of molecular light scattering at large shifts of frequencies. In particular, it has been shown that the density dependence of pressure at P>10³ MPa allowed to calculate the steepness exponent of the repulsive potential as a fitting parameter of the equation of state which possesses reliable extrapolation properties under extrapolating experimental PVT data in the high-pressure region. Processing of experimental data on a base of the statistical equation of state reveals the temperature dependence of the steepness parameter. The similar situation is also typical for the light scattering spectra. So for argon the value of this parameter varies from 15 to 10 in the gas phase and up to 24–28 in the liquid phase. The results obtained with the help of the equation of state and molecular light scattering spectra correlate well.