title: Vibrational density of states and Lindemann melting law.
abstract: We examine the Lindemann melting law at different pressures using the vibrational density of states (DOS), equilibrium melting curve, and Lindemann parameter delta(L) (fractional root-mean-squared displacement, rmsd, at equilibrium melting) calculated independently from molecular dynamics simulations of the Lennard-Jones system. The DOS is obtained using spectra analysis of atomic velocities and accounts for anharmonicity. The increase of delta(L) with pressure is non-negligible: delta(L) is about 0.116 and 0.145 at ambient and extreme pressures, respectively. If the component of rmsd normal to a reflecting plane as in the Debye-Waller-factor-type measurements using x rays is adopted for delta(L), these values are about 0.067 (+/-0.002) and 0.084 (+/-0.003), and are comparable with experimental and calculated values for face-centered-cubic elements. We find that the Lindemann relation holds accurately at ambient and high pressures. The non-negligible pressure dependence of delta(L) suggests that caution should be exerted in applying the Lindemann law to obtaining the high pressure melting curve anchored at ambient pressure.
authors.affiliation: P-24 Plasma Physics, Los Alamos National Laboratory, Los Alamos, New Mexico 87545, USA. sluo@lanl.gov
authors.forename: Sheng-Nian
authors.initials: SN
authors.lastname: Luo
authors.forename: Alejandro
authors.initials: A
authors.lastname: Strachan
authors.forename: Damian C
authors.initials: DC
authors.lastname: Swift