Warm dense gold: effective ion–ion interaction and ionisation

ABSTRACT

Warm dense matter is a peculiar state with solid densities and temperatures 1 − 100 eV. Its ab initio description waits united efforts of quantum chemistry, condensed matter and plasma physics. We use the finite temperature Kohn–Sham density functional theory (a ‘workhorse’ in this field) to study the pressure build-up with increase of electronic temperature in crystal and amorphous warm dense matter (WDM) gold. We compare the ab initio results with the effective ion–ion interaction model and reveal the possibility to separate the free electron contribution to the total pressure in WDM and to determine the corresponding degree of ionisation. For the sake of clarity, we try to describe our findings using the proper framework of statistical physics and briefly review the free energy models for WDM.

KEYWORDS:

• Density functional theory
• excited states
• free electrons

Acknowledgments

We would like to thank Genri E. Norman for his guidance in the field of strongly coupled non-equilibrium Coulomb systems. V.V. Stegailov would like to thank Igor L. Iosilevskiy for stimulating discussions of free energy models. We gratefully acknowledge the access to the supercomputer K-100 of the Keldysh Institute of Applied Mathematics of RAS and to the supercomputer MVS-100 K of the Joint Supercomputer Center of RAS.

Disclosure statement

No potential conflict of interest was reported by the authors.

Additional information

Funding

Russian Science Foundation [grant number 14-19-01487].