A Full Dimensionality
Approach to Evaluate the Nonlinear
Optical Properties of Molecules with Large Amplitude Anharmonic Tunneling
Motions
- Publication date
- Publisher
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. <i>J. Chem. Phys.</i> <b>2009</b>, <i>131</i>, 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