Collective excitations in Hydrogen across the pressure-induced transition from molecular to atomic fluid

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Hauptverfasser: Ilenkov, I. -M., Bryk, T.
Format: Preprint
Veröffentlicht: 2025
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author Ilenkov, I. -M.
Bryk, T.
author_facet Ilenkov, I. -M.
Bryk, T.
contents Dispersion of collective excitations in fluid Hydrogen along the isothermal line T=2500~K, including the region of molecular-to-atomis fluid transition, is studied by ab initio molecular dynamics (AIMD) simulations. The obtained density dependence of the adiabatic and high-frequency speed of sound contains a plateau in the region of the molecular-to-atomic fluid transition. We show, that the five-variable thermo-viscoelastic model of generalized hydrodynamics for pure molecular H$_2$ and pure atomic (H) fluids is able to recover perfectly the AIMD-derived time correlation functions and sound eigenvalues nicely agree with the numerically estimated sound dispersion. In the region of the molecular-to-atomic fluid transition a dynamic model of chemical reacting mixture should be applied. We discuss the calculations of time correlation functions from molecular/atomic units in the reacting mixture from AIMD trajectories.
format Preprint
id arxiv_https___arxiv_org_abs_2506_20791
institution arXiv
publishDate 2025
record_format arxiv
spellingShingle Collective excitations in Hydrogen across the pressure-induced transition from molecular to atomic fluid
Ilenkov, I. -M.
Bryk, T.
Chemical Physics
Disordered Systems and Neural Networks
Dispersion of collective excitations in fluid Hydrogen along the isothermal line T=2500~K, including the region of molecular-to-atomis fluid transition, is studied by ab initio molecular dynamics (AIMD) simulations. The obtained density dependence of the adiabatic and high-frequency speed of sound contains a plateau in the region of the molecular-to-atomic fluid transition. We show, that the five-variable thermo-viscoelastic model of generalized hydrodynamics for pure molecular H$_2$ and pure atomic (H) fluids is able to recover perfectly the AIMD-derived time correlation functions and sound eigenvalues nicely agree with the numerically estimated sound dispersion. In the region of the molecular-to-atomic fluid transition a dynamic model of chemical reacting mixture should be applied. We discuss the calculations of time correlation functions from molecular/atomic units in the reacting mixture from AIMD trajectories.
title Collective excitations in Hydrogen across the pressure-induced transition from molecular to atomic fluid
topic Chemical Physics
Disordered Systems and Neural Networks
url https://arxiv.org/abs/2506.20791