Research Activities > Programs > Quantum-Classical Modeling of Chemical Phenomena

Quantum-Classical Modeling of Chemical Phenomena

CSIC Building (#406), Seminar Room 4122.

Two (unrelated) topics in quantum transport: Evaluating centroid and ring-polymer dynamics and calculating STM images for molecules on semiconductor surfaces

Mark Tuckerman

New York University

Abstract:   This talk will deal with two disjoint topics in quantum transport. In the first part of the talk, I will discuss the centroid and ring-polymer molecular dynamics approaches for approximating quantum time correlation functions from path-integral molecular dynamics calculations. I will briefly describe an efficient algorithm for ring-polymer molecular dynamics calculations, and I will propose a scheme for the self-consistent evaluation of centroid and ring-polymer time correlation functions that does not require comparison to experimental data or exact results. Examples including several low-dimensional systems and fluid para-hydrogen will be presented. In the second part of the talk, the problem of calculating STM images for organic molecules on semiconductor surfaces will be discussed. Adsorbed organic molecules are of interest for their potential applications in molecular electronics and lithography. Standard techniques for calculating STM images are based on quantum-mechanical perturbation theory. I will show that such methods break down for adsorbed molecules because of nonnegligible forces exerted by the STM tip on the molecule, and I will suggest a possible remedy.

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