Cooking strongly coupled plasmas

Abstract

We present the orbital-free method for dense plasmas which allows for efficient variable ionisation molecular dynamics. This approach is a literal application of density functional theory where the use of orbitals is bypassed by a semi-classical estimation of the electron kinetic energy through the Thomas–Fermi theory. Thanks to a coherent definition of ionisation, we evidence a particular regime in which the static structure no longer depends on the temperature: the Γ-plateau. With the help of the well-known Thomas–Fermi scaling laws, we derive the conditions required to obtain a plasma at a given value of the coupling parameter and deduce useful fits. Static and dynamical properties are predicted as well as a a simple equation of state valid on the Γ-plateau. We show that the one component plasma model can be helpful to describe the correlations in real systems.

Keywords:

• dense plasmas
• Thomas–Fermi
• orbital free

Acknowledgements

We especially thank Flavien Lambert for providing his OFMD code. Giovanni Ciccotti and Philippe Arnault are also warmly acknowledged for their careful reading and suggestions.

Disclosure statement

No potential conflict of interest was reported by the author.

Notes

1. Now ‘Strongly Coupled Coulomb Systems’ conference, whose last edition was held in Santa-Fe New-Mexico in 2014

2. In Thomas-Fermi Average Atom model, the pressure is entirely determined by the electronic density at the edge of the box