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Vibrational anharmonicity of small gold and silver clusters using the VSCF method

Mancera, Luis A.; Benoit, David M.

Authors

Luis A. Mancera

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Dr David Benoit D.Benoit@hull.ac.uk
Senior Lecturer in Molecular Physics and Astrochemistry

Abstract

We study the vibrational spectra of small neutral gold (Au2–Au10) and silver (Ag2–Au5) clusters using the vibrational self-consistent field method (VSCF) in order to account for anharmonicity. We report harmonic, VSCF, and correlation-corrected VSCF calculations obtained using a vibrational configuration interaction approach (VSCF/VCI). Our implementation of the method is based on an efficient calculation of the potential energy surfaces (PES), using periodic density functional theory (DFT) with a plane-wave pseudopotential basis. In some cases, we use an efficient technique (fast-VSCF) assisted by the Voter–Chen potential in order to get an efficient reduction of the number of pair-couplings between modes. This allows us to efficiently reduce the computing time of 2D-PES without degrading the accuracy. We found that anharmonicity of the gold clusters is very small with maximum rms deviations of about 1 cm−1, although for some particular modes anharmonicity reaches values slightly larger than 2 cm−1. Silver clusters show slightly larger anharmonicity. In both cases, large differences between calculated and experimental vibrational frequencies (when available) stem more likely from the quality of the electronic structure method used than from vibrational anharmonicity. We show that noble gas embedding often affects the vibrational properties of these clusters more than anharmonicity, and discuss our results in the context of experimental studies.

Publication Date 2016-02
Journal Physical chemistry chemical physics
Print ISSN 1463-9076
Electronic ISSN 1463-9084
Publisher Royal Society of Chemistry
Peer Reviewed Peer Reviewed
Volume 18
Issue 1
Pages 529-549
Institution Citation Mancera, L. A., & Benoit, D. M. (2016). Vibrational anharmonicity of small gold and silver clusters using the VSCF method. Physical chemistry chemical physics : PCCP, 18(1), 529-549. https://doi.org/10.1039/c5cp05283a
DOI https://doi.org/10.1039/c5cp05283a
Keywords Physical and Theoretical Chemistry; General Physics and Astronomy
Publisher URL http://pubs.rsc.org/en/content/articlelanding/2016/cp/c5cp05283a#!divAbstract
Additional Information : This document is Similarity Check deposited; : Supplementary Information; : The PCCP Owner Societies have an exclusive publication licence for this journal; OPEN ACCESS: The accepted version of this article will be made freely available after a 12 month embargo period; : Single-blind; : Received 4 September 2015; Accepted 25 November 2015; Accepted Manuscript published 25 November 2015; Advance Article published 30 November 2015; Version of Record published 17 December 2015