Equation of state of dense plasmas: Orbitalfree molecular dynamics as the limit of quantum molecular dynamics for highZ elements
Abstract
The applicability of quantum molecular dynamics to the calculation of the equation of state of a dense plasma is limited at high temperature by computational cost. Orbitalfree molecular dynamics, based on a semiclassical approximation and possibly on a gradient correction, is a simulation method available at high temperature. For a highZ element such as lutetium, we examine how orbitalfree molecular dynamics applied to the equation of state of a dense plasma can be regarded as the limit of quantum molecular dynamics at high temperature. For the normal mass density and twice the normal mass density, we show that the pressures calculated with the quantum approach converge monotonically towards those calculated with the orbitalfree approach; we observe a faster convergence when the orbitalfree approach includes the gradient correction. We propose a method to obtain an equation of state reproducing quantum molecular dynamics results up to high temperatures where this approach cannot be directly implemented. With the results already obtained for lowZ plasmas, the present study opens the way for reproducing the quantum molecular dynamics pressure for all elements up to high temperatures.
 Publication:

Physics of Plasmas
 Pub Date:
 October 2014
 DOI:
 10.1063/1.4897190
 Bibcode:
 2014PhPl...21j2701D