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Ab Initio and MM3 Studies of the Conformational Structures of Naphthalene Trimer: Comparison With Experiment

Published

Author(s)

Carlos A. Gonzalez, E C. Lim

Abstract

An ab initio study of the ground-state conformational geometries of the naphthalene trimer has been made at the MP2/6-31G and MP2/6-31+G//MP2/6-31G levels of theory. The lowest-energy structure was found to be the edge-to-face cyclic (C3h) structure in which the three equivalent naphthalene moieties are arranged with their long in-plane axes parallel. The fully optimized MP2/6-31G structure has a center-to-center intermoiety distance of 4.98 and an angle of 48 between the short in-plane axis of a naphthalene moiety and the line connecting the center-of-mass of the monomer with that of the trimer . The computed rotational constants (B = 0.00555 and C = 0.00468 cm-1) are in excellent agreement with the experimental values (B = 0.00557 and C = 0.0047 cm-1) obtained from rotational coherence spectroscopy of jet-cooled naphthalene trimer (see the companion Letter by Benharash, Gleason, and Felker). Molecular mechanics (MM3) calculations also yield the same C3h trimer as the lowest-energy structure. The result suggests that, with parametrizations of force fields to fit the ab initio (or experimental, where available) geometry/energy for selected dimers and small clusters, it may be possible to develop atom-atom empirical potentials that yield reasonable energies and conformational geometries for larger aromatic clusters.
Citation
Journal of Physical Chemistry A
Volume
103

Keywords

ab initio, aromatic clusters, naphtalene, van der Waals

Citation

Gonzalez, C. and Lim, E. (1999), Ab Initio and MM3 Studies of the Conformational Structures of Naphthalene Trimer: Comparison With Experiment, Journal of Physical Chemistry A (Accessed April 15, 2024)
Created March 1, 1999, Updated February 17, 2017