A Full Dimensionality Approach to Evaluate the Nonlinear Optical Properties of Molecules with Large Amplitude Anharmonic Tunneling Motions

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• 作者：Marc Garcia-Borr脿s ; Miquel Sol脿 ; David Lauvergnat ; Heribert Reis ; Josep M. Luis ; Bernard Kirtman
• 刊名：Journal of Chemical Theory and Computation
• 出版年：2013
• 出版时间：January 8, 2013
• 年：2013
• 卷：9
• 期：1
• 页码：520-532
• 全文大小：495K
• 年卷期：v.9,no.1(January 8, 2013)
• ISSN：1549-9626

文摘

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.