Theoretical description of collective atomic motion in liquid metals describes coupling modes
Theoretical description of collective atomic motion in liquid metals describes coupling modes lead image
Liquid metals have a variety of uses, perhaps most notably as heat transfer media due to their high thermal conductivity and ability to operate at high temperatures and low pressures. Energy can be transmitted in liquid metals, in a manner analogous to phonons in solids, with transverse and longitudinal waves through vibrations in the collective constituent atoms. A deeper theoretical framework of the wave dynamics in liquid metals is important to more fully understand the basis of their applications.
Research from del Rio et al. seeks to explain a previously observed coupling in the dynamics of liquid metals between the longitudinal and transverse waves using mode coupling theory. This coupling occurs in the less studied region of medium-scale wavevectors called the kinetic regime, where shear forces or other factors do not dampen out collective atomic oscillations.
This work focused on liquid tin, using a highly efficient quantum-mechanical approach to simulate thousands of atoms for long times. It took advantage of statistics in order to capture the full collective wave dynamics. The simulation results accurately predicted the previously observed coupled mode, which can be explained from the theoretical model as an indirect coupling between the longitudinal and transverse waves.
The discovered mechanism for the coupling was indirect, meaning the two modes can couple despite the fact that they have different symmetries, which is unusual in these systems. The authors believe the mechanism can be generalized beyond tin to all liquid metals. Their future work will be focused on a deeper understanding of these coupled modes to explain their properties in other systems.
Source: “Orbital-free density functional theory simulation of collective dynamics coupling in liquid Sn,” by Beatriz G. del Rio, Mohan Chen, Luis E. González, and Emily A. Carter, The Journal of Chemical Physics (2018). The article can be accessed at https://doi.org/10.1063/1.5040697 .
