Investigating the Impact of Non-adiabatic Effects in the Warm Dense Matter Regime*

The investigation of warm dense matter (WDM) involves exploring the significance of electron-ion interactions, also known as non-adiabatic effects, on ion dynamics. In our recent publication, we investigated the impact of non-adiabatic effects on ion self-diffusion in warm dense hydrogen, using a novel method to characterize these effects [1]. Non-adiabatic effects were included using the LAMMPS implementation of the electron force field (eFF). Our approach is a straightforward yet effective way to examine dynamic properties in WDM since it includes more physics than classical molecular dynamics while remaining computationally efficient compared to time-dependent density functional theory. Our analysis using eFF also led us to examine the impact of electron dynamics on other dynamic properties of WDM systems, such as viscosity and the dynamic structure factor, further emphasizing the importance of developing higher fidelity non-adiabatic simulation methods. Ultimately, this will enable us to better understand WDM and its properties.

1. W. A. Angermeier, B. S. Scheiner, N. R. Shaffer, and T. G. White, Philos. Trans. R. Soc. A. 381, (2023).