Berlin 2014 – wissenschaftliches Programm

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MO: Fachverband Molekülphysik

MO 4: Theory 1: Molecular Dynamics

MO 4.4: Vortrag

Montag, 17. März 2014, 15:00–15:15, BEBEL SR144

Angle-resolved coarse-grained approach for molecules with high rotational mobility — •Thomas Heinemann¹, Karol Palczynski², Joachim Dzubiella², and Sabine H. L. Klapp¹ — ¹Institut für Theoretische Physik, Technische Universität Berlin, Hardenbergstr. 36, 10623 Berlin — ²Institut für Physik - Komplexe Systeme, Humboldt Universität Berlin, Newtonstr. 15, 12489 Berlin

Defining an effective potential from a statistical mechanics point of view states back to Kirkwood [1], who introduced the potential of mean force. For a two-molecule system it can be used as an effective pair potential, if the configuration entropy is removed. This entropy represents the number of atomic states for each macroscopic state. The resulting pair potential is temperature dependent.
A method is introduced, which is capable to calculate the angle-resolved effective pair potential using steered dynamics only. Results are compared to those from umbrella sampling. Constraints or restraints are only attached to the center of mass distance. In our investigations, we focused on coronene molecules, bearing no charges, as a benchmark system. The coarse-grained potential is then mapped onto a modified version of the Gay-Berne potential with minor improvements, such as contact distance [2]. A qualitative comparison between the all-atom and coarse-grained-fitted model is presented using many-particle simulations in the isotropic and hexagonal columnar regime.
J. G. Kirkwood, J. Chem. Phys. 3, 300 (1935).
F. de J. Guevara-Rodríguez and G. Odriozola, J. Chem. Phys. 135, 084508 (2011).