Direct evidence of non-acoustic collective modes in dynamics of molten Carbon
Year: 2026
Type: article
Abstract: Understanding the structure and dynamics of molten Carbon extends beyond the study of carbon-rich planetary interiors, with perspective applications in nuclear fusion, material science and industrial processes. While the recent X-ray observation of liquid C rekindled the interest in its microscopic structure, it also reminds of the challenges in rationalising the complex dynamics extending beyond the hydrodynamic regime. Primary among them is the theoretical description of non-hydrodynamic processes in one-component liquids. Here, we report collective longitudinal and transverse propagating modes in molten Carbon at T = 5500 K and pressure range 10-40 GPa from ab initio simulations and machine learned molecular dynamics. We observe an unusual two-peak shape of the longitudinal current spectral functions pointing at a branch of non-acoustic propagating modes in the wave number range k > 1 Å −1 . By applying a generalized collective modes framework to recover the time dependence of time correlations in the system, we identify the peak at lower energy as a non-hydrodynamic mode, and ascribe it to out-of-phase motion of particles encapsulated in cages of their nearest neighbors.
Source: Communications Physics
Institutions: National Academy of Sciences of Ukraine, Yukhnovskii Institute for Condensed Matter Physics of the National Academy of Sciences of Ukraine, Lviv Polytechnic National University, Italian Institute of Technology, Sapienza University of Rome, Laboratoire de Chimie et Physique - Approche Multi-échelle des Milieux Complexes, Université Paul Verlaine - Metz, Université de Lorraine, Institut polytechnique de Grenoble, Centre National de la Recherche Scientifique, Science et Ingénierie des Matériaux et Procédés, Université Grenoble Alpes
Language: English
Subfield: Materials Chemistry
Field: Materials Science
Domain: Physical Sciences
Open Access status: gold
Estimated APC paid: $3,990
OpenAlex ID: W7147494405