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MM: Fachverband Metall- und Materialphysik

MM 24: Transport II: Thermal and Electrical Conductivity

MM 24.2: Vortrag

Dienstag, 17. März 2015, 12:00–12:15, H 0107

Microscopic theory and ab initio simulation of atomic heat transport — •Aris Marcolongo¹, Stefano Baroni², and Paolo Umari³ — ¹Ecole Polytechnique Federale de Lausanne, Switzerland — ²SISSA – International School for Advanced Studies, Trieste, Italy — ³Department of Physics and Astronomy, Padua University, Italy

Green Kubo formulas, combined with classical molecular dynamics, are often used to compute thermal conductivity coefficients of liquid systems. Nevertheless, application to ab-initio molecular dynamics is often believed to be problematic because a suitable quantum-mechanical definition of the heat current is not readily available, due to the ill-definedness of the microscopic energy density to which it is related by the continuity equation. We argue that a similar difficulty actually exists in classical mechanics as well and show that it is nevertheless possible to obtain a physically well defined transport coefficient, independent of the ill defined microscopic energy density. We then derive an expliticit expression for the adiabatic energy current within density-functional theory, well defined under periodic boundary conditions. The resulting methodology is demonstrated by comparing ab initio and classical molecular simulations of a model liquid-Argon system, for which accurate inter-atomic potentials are derived by the force-matching method.