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A combined Monte Carlo and Hückel theory simulation of orientational ordering in C60 assemblies

Leaf, Jeremy; Stannard, Andrew; Jarvis, Samuel Paul; Moriarty, Philip; Dunn, Janette L.

Authors

Jeremy Leaf

Andrew Stannard

Samuel Paul Jarvis

Janette L. Dunn



Abstract

Orientational ordering of C60 molecules within monolayer and multilayer islands is a regularly observed phenomenon in scanning tunnelling microscopy (STM) studies. Here we simulate the orientational ordering seen in STM images via a novel combination of Monte Carlo and Hückel theory methods and compare to experimental data. A measure of the repulsive interaction energy between two adjacent C60 molecules is pre-calculated by estimating and processing the electron density distribution between them. Many combinations of molecular orientations are considered to encompass all the detail of the molecular orbitals. Pre-calculated intermolecular interaction energies are inputted into a simulated C60 island. Here, the center position of each molecule is fixed, but the molecules are allowed to rotate freely around their centers. A minimum in the total island free energy is sought by sequentially picking molecules at random and rotating them according to their neighbours. Results show significant correlation with experimentally observed features in both mono and multilayered islands on a variety of different substrates.

Journal Article Type Article
Acceptance Date Mar 30, 2016
Online Publication Date Mar 30, 2016
Publication Date Apr 21, 2016
Deposit Date Apr 29, 2016
Journal Journal of Physical Chemistry C
Print ISSN 1932-7447
Electronic ISSN 1932-7455
Publisher American Chemical Society
Peer Reviewed Peer Reviewed
Volume 120
Issue 15
DOI https://doi.org/10.1021/acs.jpcc.6b00638
Keywords Fullerene, C60, Monte-Carlo, Huckel, Orientational ordering, STM
Public URL https://nottingham-repository.worktribe.com/output/784213
Publisher URL http://pubs.acs.org/doi/abs/10.1021/acs.jpcc.6b00638