Equation of state for tungsten predicted by ensemble theory

TL;DR

This paper presents a novel ab initio ensemble theory approach to accurately predict the equation of state for tungsten under extreme conditions, aligning well with experimental data and demonstrating broad applicability.

Contribution

The study introduces a direct integral approach (DIA) combined with ab initio calculations to predict tungsten's EOS, a first in the field, showcasing its accuracy and universality.

Findings

Predicted EOS matches experimental data within uncertainties.

Deviations in shock wave predictions are only 2.0%.

DIA is a reliable, parameter-free method for various materials.

Abstract

Equation of state (EOS) for bcc tungsten at 300 K (or 3000 K) up to 1000 GPa (or 300 GPa) was predicted for the first time by solving the partition function via a direct integral approach (DIA) with ab initio calculations of the atoms' interactions. Compared with available experiments under static compressions up to 150 GPa (or 35 GPa) for room temperature (or 1673 K), all the calculated results are within the experimental uncertainty achieved very recently. Furthermore, the same procedure was performed to investigate the shock wave experiments on the EOS up to 400 GPa and 10000 K, and the calculated average pressure deviates the experimental measurements by only 2.0%. These facts suggest that the other calculated results of DIA for the EOS are reliable, and DIA as a universal method without any artificial parameters could be widely applied to predict EOS of various materials under various conditions.