Recent findings of pressure-induced emergence of unusual high-frequency contribution to transverse current spectral functions in several simple liquid metals at high pressures raised a question whether similar features can be observed in liquid metals at ambient conditions. We report here analysis of ab initio molecular dynamics-derived longitudinal and transverse current spectral functions and corresponding dispersions of collective excitations in liquid polyvalent metals Al, Tl, Ni. We have not found evidences of the second branch of high-frequency transverse modes in liquid Al and Ni, while in the case of liquid Tl they were clearly present in transverse dynamics. The vibrational density of states for liquid Tl has a pronounced high-frequency shoulder, which is located right in the frequency range of the second high-frequency transverse branch, while for liquid Al and Ni the vibrational density of states has only a weak indication of possible high-frequency shoulder. The origin of specific behavior of transverse excitations in liquid Tl is discussed.
Collective dynamics of metallic melts at high pressures is one of the open issues of condensed matter physics. By means of ab initio molecular dynamics simulations, we examine features of dispersions of collective excitations through transverse current spectral functions, as a function of pressure. Typical metallic melts, such as Li and Na monovalent metals as well as Al, Pb and In polyvalent metals are considered. We firmly establish the emergence of a second branch of high-frequency transverse modes with pressure in these metals, that we associate with the pronounced high-frequency shoulder in the vibrational density of states. Similar correlation also exist with the low frequency modes. The origin of the pressure-induced evolution of transverse excitations in liquid metals is discussed.
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.