Dispersion of acoustic excitations in tetrahedral liquids

TL;DR

This paper investigates how the dispersion of acoustic excitations in liquids like water and silicon varies with temperature and density, revealing anomalous behaviors especially in water, which enhances understanding of liquid state dynamics.

Contribution

It provides a comparative analysis of dispersion curves in water and silicon, highlighting the pronounced anomaly in water's acoustic excitations.

Findings

Both water and silicon show dispersion anomalies.

Water exhibits a more pronounced anomaly.

Dispersion behaviors depend on temperature and density.

Abstract

Investigation of the longitudinal and transverse excitations in liquids is of great importance for understanding the fundamentals of the liquid state of matter. One of the important questions is the temperature and density dependence of the frequency of the excitations. In our recent works it was shown that while in simple liquids the frequency of longitudinal excitations increases when the temperature is increased isochorically, in water the frequency can anomalously decrease with the temperature increase. In the present manuscript we study the dispersion curves of longitudinal and transverse excitations of water and liquid silicon modelled by Stillinger-Weber potential. We show that both substances demonstrate the anomaly of the dispersion curves, but it the case of water it is more pronounced.