On the optimal void fraction in the thermodynamics of a simple liquid

摘要

The free energy of a crystal containing a given void fraction is derived in terms of the truncated interparticle Lennard-Jones potential. The free energy is minimized over the void fraction at constant pressure and temperature. It is shown that for all pressures the optimal void fraction remains less than 1% as the temperature is raised. However, at some temperature it grows suddenly and reaches values of the order of the percolation level for voids in a crystal, approx 0.125. At this point, the crystal transitions to the liquid state takes place. The derived dependence of the transition temperature on the pressure-the melting curve-is in good agreement with experimental data on the melting of solidified inert gases.