A new quotidian equation of state (QEOS) for hot dense matter

TLDR

The quotidian equation of state (QEOS) is a general‑purpose model for hydrodynamic simulations of high‑pressure phenomena, offering smooth predictions for ionization state, pressure, energy, entropy, and Helmholtz free energy. The paper evaluates the resulting thermodynamic data, comparing QEOS predictions with other theories and shock‑wave measurements. QEOS derives electronic properties from a modified Thomas–Fermi statistical model and describes ion thermal motion with a multiphase equation of state that blends Debye, Grüneisen, Lindemann, and fluid‑scaling laws, optionally applying a temperature‑dependent pressure multiplier to extend material coverage.

Abstract

The quotidian equation of state (QEOS) is a general-purpose equation of state model for use in hydrodynamic simulation of high-pressure phenomena. Electronic properties are obtained from a modified Thomas–Fermi statistical model, while ion thermal motion is described by a multiphase equation of state combining Debye, Grüneisen, Lindemann, and fluid-scaling laws. The theory gives smooth and usable predictions for ionization state, pressure, energy, entropy, and Helmholtz free energy. When necessary, the results may be modified by a temperature-dependent pressure multiplier which greatly extends the class of materials that can be treated with reasonable accuracy. In this paper a comprehensive evaluation of the resulting thermodynamic data is given including comparison with other theories and shock-wave data.