Fully coupled six-dimensional calculations of the water dimer vibration-rotation-tunneling states with split Wigner pseudospectral approach. II. Improvements and tests of additional potentials

Abstract

Fully coupled 6D calculations of the ammonia vibration-inversion-tunneling states with a split Hamiltonian pseudospectral approach J. Chem. Phys. 111, 7236 (1999); 10.1063/1.480099Six-dimensional quantum calculation of the intermolecular bound states for water dimer Fully coupled six-dimensional calculations of the water dimer vibration-rotation-tunneling states with a split Wigner pseudo spectral approachThe SWPS method is improved by the addition of H.E.G. contractions for generating a more compact basis. An error in the definition of the internal fragment axis system used in our previous calculation is described and corrected. Fully coupled 6D ͑rigid monomers͒ VRT states are computed for several new water dimer potential surfaces and compared with experiment and our earlier SWPS results. This work sets the stage for refinement of such potential surfaces via regression analysis of VRT spectroscopic data.

Vibration–rotation-tunneling states of the benzene dimer: an ab initio study

“…Our work on the Ar-benzene complex, 102-104 the ammonia dimer, 53 and the water dimer [56][57][58][59][60][61][62] has shown that the comparison of calculated VRT levels with experimental (high-resolution) spectroscopic data is an excellent way to check and, if needed, improve the quality of intermolecular potential surfaces. Although much experimental data is available also for the benzene dimer, most of these data consists of UV, Raman, and infrared spectra that address the properties of the (perturbed) monomers.…”

“…The methods that have been developed [53][54][55][56][57] to compute the VRT states of a weakly bound dimer start from the Hamiltonian of a rotating dimer with two internally rotating (rigid) polyatomic monomers, expressed in body-fixed (BF) dimer coordinates…”

“…[54][55][56][57]61,62 Just as in the earlier work on the NH 3 and water dimers, we introduce a coupled product basis of symmetric rotor functions-Wigner D-functions 97 -for the angular coordinates…”

“…One-dimensional model studies of some tunneling processes in the benzene dimer and a harmonic (normal mode) calculation of the intermolecular vibrations have been made by Spirko et al 31 A quantum mechanical method applicable to weakly bound dimers that includes all six (coupled) intermolecular degrees of freedom has been developed [53][54][55][56] and successfully applied, for example, to the ammonia dimer 53 and the water dimer. [56][57][58][59][60][61][62] A global six-dimensional intermolecular potential surface is needed in such a treatment. This has led to a useful understanding of the nature of the internal motions in these systems and to an interpretation of the experimental spectra.…”

Water Dimers in the Atmosphere II: Results from the VRT(ASP-W)III Potential Surface

“…Only recently have rigorous models for the dimer potential and rigorous methods for computing concentrations from them been developed. [18][19][20] Recent measurements 2,21 have shown that the absorption of solar flux at dimer vibrational overtone wavelengths predicted in ref 2 is negligibly small. 1,21 However, the very recent article by Pfeilsticker et al 22 reports measured dimer atmospheric absorption the intensities of which are in agreement with values determined via a combination of calculated water dimer line strengths by Low and Kjaergaard 23 and the classic laboratory experiments of Curtiss et al 24 Their results are lower than absorption intensities determined using our results for K P calculated on the original VRT(ASP-W) potential.…”