The Accuracy, Consistency, and Speed of an ElectronPositron Equation of State Based on Table Interpolation of the Helmholtz Free Energy
Abstract
An electronpositron equation of state based on table interpolation of the Helmholtz free energy is developed and analyzed. The interpolation scheme guarantees perfect thermodynamic consistency, independent of the interpolating function. The choice of a biquintic Hermite polynomial as the interpolating function results in accurately reproducing the underlying Helmholtz free energy data in the table, and yields derivatives of the pressure, specific entropy, and specific internal energy which are smooth and continuous. The execution speedevaluated across several different machine architectures, compiler options, and modes of operationsuggests that the Helmholtz equation of state routine is faster than any of the five equation of state routines surveyed by Timmes & Arnett. When an optimal balance of accuracy, thermodynamic consistency, and speed is desirable then the tabular Helmholtz equation of state is an excellent choice, particularly for multidimensional models of stellar phenomena.
 Publication:

The Astrophysical Journal Supplement Series
 Pub Date:
 February 2000
 DOI:
 10.1086/313304
 Bibcode:
 2000ApJS..126..501T
 Keywords:

 EQUATION OF STATE;
 HYDRODYNAMICS;
 METHODS: NUMERICAL;
 STARS: GENERAL;
 Equation of State;
 Hydrodynamics;
 Methods: Numerical;
 Stars: General