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Advances in Physical Chemistry
Volume 2012 (2012), Article ID 951371, 9 pages
http://dx.doi.org/10.1155/2012/951371
Research Article

Improved Potential Energy Surface of Ozone Constructed Using the Fitting by Permutationally Invariant Polynomial Function

Chemistry Department, Marquette University, Wehr Chemistry Building, Milwaukee, WI 53201-1881, USA

Received 7 July 2011; Accepted 23 August 2011

Academic Editor: Joel Bowman

Copyright © 2012 Mehdi Ayouz and Dmitri Babikov. This is an open access article distributed under the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.

Abstract

New global potential energy surface for the ground electronic state of ozone is constructed at the complete basis set level of the multireference configuration interaction theory. A method of fitting the data points by analytical permutationally invariant polynomial function is adopted. A small set of 500 points is preoptimized using the old surface of ozone. In this procedure the positions of points in the configuration space are chosen such that the RMS deviation of the fit is minimized. New ab initio calculations are carried out at these points and are used to build new surface. Additional points are added to the vicinity of the minimum energy path in order to improve accuracy of the fit, particularly in the region where the surface of ozone exhibits a shallow van der Waals well. New surface can be used to study formation of ozone at thermal energies and its spectroscopy near the dissociation threshold.