Abstract:
An analytical method is proposed for calculating the lattice and surface properties of rhodium (Rh) at any (corresponding to the solid phase) values of temperature $T$ and pressure $P$. Within the framework of this method, the parameters of the pairwise interatomic Mie–Lennard-Jones potential for Rh are determined in a self-consistent manner. The obtained potential parameters were tested by calculating the equation of state and baric dependences of the elastic modulus $(B_T)$ and the thermal expansion coefficient. Using this analytical method, the surface properties of rhodium were studied for the first time: specific surface energy $(\sigma)$ and derivatives of $\sigma$ in temperature and pressure: $\sigma'(P)_T=(\partial\sigma/\partial P)_T$. Both baric dependences of these functions along three isotherms: 300, 1000, 2000 K, and temperature dependences along three isobars: 0, 50, 100 GPa were obtained. Estimates for the fragmentation point of rhodium at different temperatures are obtained. It is shown that the function $\sigma'(P)$ for rhodium depends linearly on the value of the pressure derivative of the elastic modulus $B'(P)=(\partial B_T/\partial P)_T$. The dependences of Poisson's ratio on pressure and temperature have been studied. The baric dependence of the Rh melting point is calculated. The influence of the electronic subsystem on the obtained dependencies is studied.
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