title: Parametrizing linear generalized Langevin dynamics from explicit molecular dynamics simulations.
abstract: Fundamental understanding of complex dynamics in many-particle systems on the atomistic level is of utmost importance. Often the systems of interest are of macroscopic size but can be partitioned into a few important degrees of freedom which are treated most accurately and others which constitute a thermal bath. Particular attention in this respect attracts the linear generalized Langevin equation, which can be rigorously derived by means of a linear projection technique. Within this framework, a complicated interaction with the bath can be reduced to a single memory kernel. This memory kernel in turn is parametrized for a particular system studied, usually by means of time-domain methods based on explicit molecular dynamics data. Here, we discuss that this task is more naturally achieved in frequency domain and develop a Fourier-based parametrization method that outperforms its time-domain analogues. Very surprisingly, the widely used rigid bond method turns out to be inappropriate in general. Importantly, we show that the rigid bond approach leads to a systematic overestimation of relaxation times, unless the system under study consists of a harmonic bath bi-linearly coupled to the relevant degrees of freedom.
authors.affiliation: Institute of Physics, Rostock University, Universitätsplatz 3, 18055 Rostock, Germany.
authors.forename: Fabian
authors.initials: F
authors.lastname: Gottwald
authors.affiliation: Institute of Physics, Rostock University, Universitätsplatz 3, 18055 Rostock, Germany.
authors.forename: Sven
authors.initials: S
authors.lastname: Karsten
authors.affiliation: Institute of Physics, Rostock University, Universitätsplatz 3, 18055 Rostock, Germany.
authors.forename: Sergei D
authors.initials: SD
authors.lastname: Ivanov
authors.affiliation: Institute of Physics, Rostock University, Universitätsplatz 3, 18055 Rostock, Germany.
authors.forename: Oliver
authors.initials: O
authors.lastname: Kühn