10.18453/rosdok_id00005794 Roy, Argha Argha Roy http://d-nb.info/gnd/1419587161 https://orcid.org/0009-0006-4798-650X Universität Rostock 2025 530 Physics 2025 en https://purl.uni-rostock.de/rosdok/id00005794 urn:nbn:de:gbv:28-rosdok_id00005794-0 This thesis examines the thermodynamic and electronic properties of methane (CH4) - hydrogen (H2) mixtures under high pressure and temperature conditions relevant to Uranus- and Neptune-like planets. Density functional theory molecular dynamics (DFT-MD) simulations are employed to analyze the equation of state, structural changes, the influence of varying hydrogen concentrations, and to evaluate the validity of the linear mixing approximation. Furthermore, to mitigate the computational limitations of DFT-MD, a novel approach combining stochastic-DFT (sDFT) with Langevin dynamics is introduced.