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

Published

March 1, 1999

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 (C_3h) 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 C_3h 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

Pub Type

Journals

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 December 13, 2024)