Correlated Particle Motion and THz Spectral Response of Supercritical Water

TL;DR

This study uses molecular dynamics simulations to explore how supercritical water's particle motion and spectral response differ from ambient water, revealing unique vibrational and correlation behaviors at THz frequencies.

Contribution

It provides new insights into the molecular dynamics and spectral properties of supercritical water across the Widom line, highlighting changes in hydrogen bonding and particle correlations.

Findings

Distinct distance-dependent dipolar response in supercritical water

Significant spectral differences above and below the Widom line

Altered vibrational density of states at THz frequencies

Abstract

Molecular dynamics simulations of supercritical water reveal distinctly different distance-dependent modulations of dipolar response and correlations in particle motion compared to ambient conditions. The strongly perturbed H-bond network of water at supercritical conditions allows for considerable translational and rotational freedom of individual molecules. These changes give rise to substantially different infrared spectra and vibrational density of states at THz frequencies for densities above and below the Widom line that separates percolating liquid-like and clustered gas-like supercritical water.