ABSTRACT
Accurate ab initio computations of structural and spectroscopic parameters for the HPS/HSP molecules and corresponding cations and anions have been performed. For the electronic structure computations, standard and explicitly correlated coupled cluster techniques in conjunction with large basis sets have been adopted. In particular, we present equilibrium geometries, rotational constants, harmonic vibrational frequencies, adiabatic ionization energies, electron affinities, and, for the neutral species, singlet-triplet relative energies. Besides, the full-dimensional potential energy surfaces (PESs) for HPS(x) and HSP(x) (x = -1,0,1) systems have been generated at the standard coupled cluster level with a basis set of augmented quintuple-zeta quality. By applying perturbation theory to the calculated PESs, an extended set of spectroscopic constants, including τ, first-order centrifugal distortion and anharmonic vibrational constants has been obtained. In addition, the potentials have been used in a variational approach to deduce the whole pattern of vibrational levels up to 4000 cm(-1) above the minima of the corresponding PESs.
ABSTRACT
This work reports the results of high level ab initio calculations of the PN-HNP(+) complex and the corresponding hydrogen migration transition state. The geometries, rotational constants, harmonic vibrational frequencies, and energetics of each species involved in the complex are reported. A reduced dimensional 2D and 4D potential energy surface is constructed and used to obtain 2D and 4D vibrational states. The results of this study show excellent correlation to available experimental data for PN. The presented results can facilitate both laboratory and interstellar observations of this novel and strongly interacting linear proton-bound complex.
ABSTRACT
This work reports the results of high level ab initio calculations of the OC-HCO(+) complex and the SC-HCS(+) complex and their hydrogen migration transition states. Geometry optimizations are performed at the CCSD(T)/aug-cc-pV5Z level of theory. Subsequent frequency calculations are carried out at the CCSD(T)/aug-cc-pVQZ level of theory. Additional geometry optimizations and harmonic frequency calculations for all the species involved in this study have been done with the explicitly correlated CCSD(T)-F12 method with the aug-cc-pVTZ and VTZ-F12 basis set. The geometries, rotational constants, harmonic vibrational frequencies, and energetics of the species involved in the complex are reported. These methods result in accurate computational predictions that have mean deviations for bond lengths, rotational constants, and vibrational frequencies of 0.001 Å, 163 MHz, and 46 cm(-1), respectively. These results provide essential spectroscopic properties for the complexes that can facilitate both laboratory and interstellar observations, and they also provide a comparison between oxygen and sulfur complex observability based on thermodynamic stability.
