Velocity autocorrelations across the molecular—atomic fluid transformation in hydrogen under pressure

Giancarlo Ruocco (1) , Taras M. Bryk (2, 3) , Carlo Pierleoni (4, 5) , Ari Paavo Seitsonen (6)

1 UNIROMA - Università degli Studi di Roma "La Sapienza" = Sapienza University [Rome]
2 ICMP - Institute for Condensed Matter Physics of NAS of Ukraine
3 LPNU - National Polytechnic University of Lviv
4 MDLS - Maison de la Simulation
5 DSFC - Department of Physical and Chemical Sciences [L'Aquila]
6 Département de Chimie - ENS Paris

Non-monotonous changes in velocity autocorrelations across the transformation from molecular to atomic fluid in hydrogen under pressure are studied by ab initio molecular dynamics simulations at the temperature 2500 K. We report diffusion coefficients in a wide range of densities from purely molecular fluid up to metallic atomic fluid phase. An analysis of contributions to the velocity autocorrelation functions from the motion of molecular centers-of-mass, rotational and intramolecular vibrational modes is performed, and a crossover in the vibrational density of intramolecular modes across the transition is discussed.

Domaines: Dynamique des Fluides [physics.flu-dyn]

Giancarlo Ruocco, Taras M. Bryk, Carlo Pierleoni, Ari Paavo Seitsonen. Velocity autocorrelations across the molecular—atomic fluid transformation in hydrogen under pressure. Condensed Matter Physics, 2020, 23 (2), pp.23607. ⟨10.5488/CMP.23.23607⟩. ⟨cea-04069219⟩