title: A Full Dimensionality Approach to Evaluate the Nonlinear Optical Properties of Molecules with Large Amplitude Anharmonic Tunneling Motions.
abstract: Previously, a reduced dimensionality approach was used to determine the vibrational contribution to nonlinear optical properties for molecules with large amplitude anharmonic modes that takes into account tunneling between potential wells (Luis, J. M.; Reis, H.; Papadopoulos, M. G.; Kirtman, B. J. Chem. Phys.2009, 131, 034116). Here, the treatment is extended, again using ammonia as an example, to include the remaining modes at several approximate levels. It is shown that this extension is essential to obtaining the correct results. Our new approach fully accounts for tunneling and avoids possible convergence problems associated with the normal coordinate expansion of the potential energy surface in a single-well treatment. For accurate numerical values, a good treatment of electron correlation is required along with a flexible basis set including diffuse functions.
authors.affiliation: Institut de Química Computacional and Departament de Química, Universitat de Girona, Campus Montilivi, 17071 Girona, Catalonia, Spain.
authors.forename: Marc
authors.initials: M
authors.lastname: Garcia-Borràs
authors.affiliation: Institut de Química Computacional and Departament de Química, Universitat de Girona, Campus Montilivi, 17071 Girona, Catalonia, Spain.
authors.forename: Miquel
authors.initials: M
authors.lastname: Solà
authors.affiliation: Laboratoire de Chimie Physique, CNRS, Bât. 349, UMR 8000, Orsay F-91405, France and Université Paris-Sud, Orsay F-91405, France.
authors.forename: David
authors.initials: D
authors.lastname: Lauvergnat
authors.affiliation: Institute of Biology, Medicinal Chemistry and Biotechnology, National Hellenic Research Foundation, 48 Vas. Constantinou Ave., Athens 116 35, Greece.
authors.forename: Heribert
authors.initials: H
authors.lastname: Reis
authors.affiliation: Institut de Química Computacional and Departament de Química, Universitat de Girona, Campus Montilivi, 17071 Girona, Catalonia, Spain.
authors.forename: Josep M
authors.initials: JM
authors.lastname: Luis
authors.affiliation: Department of Chemistry and Biochemistry, University of California, Santa Barbara, California 93106, United States.
authors.forename: Bernard
authors.initials: B
authors.lastname: Kirtman