title: Markovian dissipative coarse grained molecular dynamics for a simple 2D graphene model.
abstract: Based upon a finite-element "coarse-grained molecular dynamics" (CGMD) procedure, as applied to a simple atomistic 2D model of graphene, we formulate a new coarse-grained model for graphene mechanics explicitly accounting for dissipative effects. It is shown that, within the Mori-projection operator formalism, the reversible part of the dynamics is equivalent to the finite temperature CGMD-equations of motion, and that dissipative contributions to CGMD can also be included within the Mori formalism. The CGMD nodal momenta in the present graphene model display clear non-Markovian behavior, a property that can be ascribed to the fact that the CGMD-weighting function suppresses high-frequency modes more effectively than, e.g., a simple center of mass (COM) based CG procedure. The present coarse-grained graphene model is also shown to reproduce the short time behavior of the momentum correlation functions more accurately than COM-variables and it is less dissipative than COM-CG. Finally, we find that, while the intermediate time scale represented directly by the CGMD variables shows a clear non-Markovian dynamics, the macroscopic dynamics of normal modes can be approximated by a Markovian dissipation, with friction coefficients scaling like the square of the wave vector. This opens the way to the development of a CGMD model capable of describing the correct long time behavior of such macroscopic normal modes.
authors.affiliation: School of Soft Matter Research, Freiburg Institute for Advanced Studies, University of Freiburg, Albertstr. 19, 79104 Freiburg, Germany. david.kauzlaric@frias.uni-freiburg.de
authors.forename: David
authors.initials: D
authors.lastname: Kauzlarić
authors.forename: Pep
authors.initials: P
authors.lastname: Español
authors.forename: Andreas
authors.initials: A
authors.lastname: Greiner
authors.forename: Sauro
authors.initials: S
authors.lastname: Succi