Analysis of localization sites for an excess electron in neutral methanol clusters using approximate pseudopotential quantum-mechanical calculations

Mones, Letif; Rossky, Peter J.; Turi, László

doi:doi:10.1063/1.3503506

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We have used a recently developed electron-methanol molecule pseudopotential in approximate quantum mechanical calculations to evaluate and statistically analyze the physical properties of an excess electron in the field of equilibrated neutral methanol clusters ((CH₃OH)_n, n = 50–500). The methanol clusters were generated in classical molecular dynamics simulations at nominal 100 and 200 K temperatures. Topological analysis of the neutral clusters indicates that methyl groups cover the surface of the clusters almost exclusively, while the associated hydroxyl groups point inside. Since the initial neutral clusters are lacking polarity on the surface and compact inside, the excess electron can barely attach to these structures. Nevertheless, most of the investigated cluster configurations do support weakly stabilized cluster anion states. We find that similarly to water clusters, the pre-existing instantaneous dipole moment of the neutral clusters binds the electron. The localizing electrons occupy diffuse, weakly bound surface states that largely engulf the cluster although their centers are located outside the cluster molecular frame. The initial localization of the excess electron is reflected in its larger radius compared to water due to the lack of free OH hydrogens on the cluster surface. The stabilization of the excess electron increases, while the radius decreases monotonically as the clusters grow in size. Stable, interior bound states of the excess electron are not observed to form neither in finite size methanol clusters nor in the equilibrium bulk.

Article Outline

INTRODUCTION
METHODS
RESULTS
1. Structural properties of the neutral methanol clusters
2. Binding properties of the excess electron to neutral methanol clusters
DISCUSSION AND CONCLUSIONS

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KEYWORDS and PACS

Keywords

electron attachment, localised states, molecular clusters, molecular dynamics method, negative ions, organic compounds, pseudopotential methods, surface states

PACS

36.40.Cg

Electronic and magnetic properties of clusters
34.80.Lx

Recombination, attachment, and positronium formation

ARTICLE DATA

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http://dx.doi.org/10.1063/1.3503506

PUBLICATION DATA

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0021-9606 (print)

1089-7690 (online)

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$abstract.society.value is a Member of CrossRef

American Institute of Physics

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