Size dependence of elastic properties of argon nanocrystals

The state equation $(P)$ and isothermal elastic modulus $(B)$ are calculated for argon macro- and nanocrystals at $T$ = 10 K using in the framework the RP(vac)-model of nanocrystal. The isochoric and isobaric (at $P$ = 0) dependences of the Debye temperature $(\Theta)$, of the first ($\gamma$) and second $(q)$ Grüneisen parameters, as well as the specific surface energy ($\sigma$), $B$ and $B'(P)= (\partial B /\partial P)_T$, are studied as the functions of size and shape of the nanocrystal. As shown, the isothermally isobaric decrease in nanocrystal size is accompanied by a decrease in functions $\Theta$, $q$, $\sigma$, $B$ and $B'(P)$ and by an increase in the $\gamma$ parameter. However, the elastic modulus rises in the case of the isothermally isochoric decrease in the nanocrystal size. When the nanocrystal deviates from its most energetically optimal shape (a cube for the RP(vac)-model), the size dependences of these functions become more noticeable.