231 research outputs found
Kinetic Schemes in Open Interacting Systems
We discuss utilization of kinetic schemes for description of open interacting
systems, focusing on vibrational energy relaxation for an oscillator coupled to
a nonequilibirum electronic bath. Standard kinetic equations with constant rate
coefficients are obtained under the assumption of timescale separation between
system and bath, with the bath dynamics much faster than that of the system of
interest. This assumption may break down in certain limits and we show that
ignoring this may lead to qualitatively wrong predictions. Connection with more
general, nonequilibrium Green's function (NEGF) analysis, is demonstrated. Our
considerations are illustrated within generic molecular junction models with
electron-vibration coupling.Comment: 22 pages, 4 figure
Nuclear dynamics at molecule-metal interfaces: A pseudoparticle perspective
We discuss nuclear dynamics at molecule-metal interfaces including
non-equilibrium molecular junctions. Starting from the many-body states
(pseudoparticle) formulation of the molecule-metal system in the molecular
vibronic basis, we introduce gradient expansion in order to reduce the
adiabatic nuclear dynamics (that is, nuclear dynamics on a single molecular
potential surface) into its semi-classical form while maintaining the effect of
the non-adiabatic electronic transitions between different molecular charge
states. This yields a set of equations for the nuclear dynamics in the presence
of these non-adiabatic transitions, which reproduce surface hopping formulation
in the limit of small metal-molecule coupling (where broadening of the
molecular energy levels can be disregarded) and Ehrenfest dynamics (motion on
the potential of mean force) when information on the different charging states
is traced out, which is relevant when this coupling is strong.Comment: 9 page
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