Ab initio computational spectroscopy and vibrational dynamics of polyatomic molecules: Applications to syn and anti-CH3CHOO and NO3

This article describes theoretical/computational techniques that are aimed at addressing both vibrational spectroscopy and large-amplitude nuclear dynamics. Two new examples from our group are discussed in detail. These are the syn and anti-conformers of the Crigee intermediate CH3CHOO and isotope effects in the nitrate radical vibrational energies. For both, potential energy surfaces that are mathematical fits to thousands of electronic energies are described. Dipole moment surfaces for syn and anti-CH3CHOO are also described. These surfaces are used in new, full-dimensional vibrational calculations for syn and anti-CH3CHOO and survey infrared spectra are reported up to 6200 cm(-1). For NO3 the focus is on further studies of isotope effects, using an adiabatic PES that was recently reported in a study of the vibrational energies of (NO3)-N-14-O-16 and (NO3)-N-15-O-16 (Homayoon and Bowman, 2014). (C) 2014 Elsevier Inc. All rights reserved.