EOS from first principles to hydrocodes

First-Principles and Molecular Dynamics are now abundant sources of data to build EOS in analytical or tabulated form for use in high pressure hydrocode simulations.

We propose to show a method in three simple steps that provides analytical EOS for the phases given by such points. Variations of this method allow to solve the problem for different kinds of data. The main idea is to check thermodynamic consistency of the data and focus on some selected correlations, with least squares methods.

The first step consist in checking the Mie-Grüneisen assumption from which we build the Grüneisen coefficient and deduce the Debye temperature.

In the second step, we build a cold potential Ec versus volume.and obtain a Mie-Grüneisen incomplete EOS useful for most shock waves problems. In the third step we use temperature to obtain a complete EOS. We can detect here a phase transition and obtain the entropy with a very good accuracy.

For pratical use in hydrocodes, we build a smart tabulation which provides fast and accurate access to the required values. The grid in described in a small xml file (less than 1 Mo) which describes the phase diagram from which we access a part of a cell and use its analytical EOS (phase, binary mixture or triple point).

We show the application for different materials.