Specific heats for simple molecular fluids from molecular dynamics simulations

Abstract
Residual specific heats C res v are obtained from molecular dynamics (MD) simulations for the two-centre (2CLJ) and three-centre Lennard-Jones (3CLJ) models of liquid ethane and propane. The C res v values calculated from fluctuation theory show significant rises in the liquid near the liquid-vapour transition line, in agreement with experiment. A non-linear two parameter function fitted to simulations of U res is shown to give heat capacities consistent with those obtained from the fluctuation calculation. It is also shown how results obtained from the (NVE) simulations compare with (NVT) simulations based on a momentum-scaling algorithm.