Abstract:
State equation $P(V/V_{0},T)$ and baric dependences of thermal properties of diamond have been obtained without any fitting parameters from the interatomic pair Mie–Lennard-Jones potential and the Einstein model of a crystal. Calculations have been performed along two isotherms (at $T$ = 300 and 3000 K) up to $P$ = 10000 kbar = 1000 GPa, i.e., to a relative volume of $V/V_0$ = 0.5. The baric dependences have been obtained for the following characteristics: isothermal elastic modulus $B_T$ and $B'(P)$, isochoric heat capacity $C_v$ and
$C_v'(P)$, isobaric heat capacity $C_p$; thermal expansion coefficient $\alpha_p$ and $\alpha'_{p}(P)$; and specific surface energy $\sigma$, as well as its derivatives $\sigma'(P)$ and $\sigma'(T)$. It is shown that for $P\to\infty$, functions $B_T(P)$ and $\sigma(P)$ vary linearly, functions $B'(P)$, $\alpha_{p}(P)$, $C_{v}(P)$, $C_{p}(P)$, and $\sigma'(P)$ tend to constants, while functions $\alpha_p'(P)$, $C_v'(P)$, and difference $C_p(P)$ – $C_v(P)$ tend to zero. Good agreement with experimental data has been demonstrated.
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