Change in the thermophysical properties of BCC iron during isothermal compression

Equation of state $P(V/V_0,T)$ and baric dependences of the thermodynamic properties of bcc iron are obtained using the Mie–Lennard-Jones interatomic pair potential and the Einstein model of a crystal without any adjustable parameters. The calculations performed along two isotherms at 300 and 1500 K from $P$ = 0 to 8000 kbar = 800 GPa (i.e., to $V/V_0$ = 0.5) show good agreement with the experimental data. Baric graphical dependences are obtained for the following properties: isothermal bulk modulus $B_T$ and $B'(P)$, isochoric specific heat $C_v$ and $C'_v(P)$, isobaric specific heat $C_p$, thermal expansion coefficient $\alpha_p$ and $\alpha'_p(P)$, and specific surface energy of (100) face $\sigma$ and $\sigma'(P)$. Analytical approximations are obtained for baric dependences $B'(P)$, $\alpha_p(P)$, and $\sigma'(P)$. It is shown that, at $P\to\infty$, functions $B_T(P)$ and $\sigma(P)$ for bcc iron change linearly and function $\alpha'_p(P)$ tends toward zero.