Exchange-correlation entropy from the generalized thermal adiabatic connection

Brittany P Harding; Zachary Mauri; Vera W Xie; Aurora Pribram-Jones

doi:10.1063/5.0196650

Exchange-correlation entropy from the generalized thermal adiabatic connection

J Chem Phys. 2024 Apr 21;160(15):154108. doi: 10.1063/5.0196650.

Authors

Brittany P Harding¹, Zachary Mauri², Vera W Xie¹, Aurora Pribram-Jones¹

Affiliations

¹ University of California, Merced, 5200 North Lake Road, Merced, California 95343, USA.
² Stanford University, 450 Jane Stanford Way, Stanford, California 94305, USA.

PMID: 38629600
DOI: 10.1063/5.0196650

Abstract

Warm dense matter is a highly energetic phase characterized by strong correlations, thermal effects, and quantum mechanical electrons. Thermal density functional theory is commonly used in simulations of this challenging phase, driving the development of temperature-dependent approximations to the exchange-correlation free energy. Approaches using the adiabatic connection formula are well known at zero temperature and have been recently leveraged at non-zero temperatures as well. In this work, a generalized thermal adiabatic connection (GTAC) formula is proposed, introducing a fictitious temperature parameter. This allows extraction of the exchange-correlation entropy SXC using simulated interaction strength scaling. This procedure uses a Hellmann-Feynman approach to express the exchange-correlation entropy in terms of a temperature- and interaction strength-dependent exchange-correlation potential energy. In addition, analysis of SXC as a function of interaction strength suggests new forms for approximations, and GTAC itself offers a new framework for exploring both the exact and approximate interplay of temperature, density, and interaction strength across a wide range of conditions.