Thermal energy of the crystalline one-component plasma from dynamical simulations.

Abstract

Molecular-dynamics simulations employing 1024 particles and a high-accuracy spline approximation of the Ewald potential have been used to measure the excess internal energy of the classical one-component plasma in both the fluid and solid (bcc) phases over a wide range (1\ensuremath{\le}\ensuremath{\Gamma}\ensuremath{\le}2000) of the coupling parameter. The energy data for \ensuremath{\Gamma}\ensuremath{\le}300 are in excellent agreement with previous Monte Carlo calculations for this range, giving an independent corroboration of these calculations. Data in the crystalline regime 170\ensuremath{\le}\ensuremath{\Gamma}\ensuremath{\le}2000 are used to estimate the coefficients of the anharmonic energy component by least-squares fits. The first coefficient is in reasonable agreement with peturbation-theory predictions, although it is argued that determination of the coefficients in this manner is a rather ill-conditioned problem. The free-energy curves of the fluid and solid phases are found to cross at ${\mathrm{\ensuremath{\Gamma}}}_{\mathit{m}}$\ensuremath{\approxeq}173, in agreement with recent estimates.