Ab initio study of the vibronic spectrum in the X 2Π electronic state of HCCS

Abstract

Articles you may be interested inAccurate ab initio ro-vibronic spectroscopy of the X ̃ 2 Π CCN radical using explicitly correlated methods An ab initio study of the vibronic, spin-orbit, and magnetic hyperfine structure in the X Π 2 electronic state of NCO An ab initio study of the hyperfine structure in the X 2 Π electronic state of CCCH Ab initio study of the vibronic and spin-orbit structure in the X 2 Π electronic state of CCCH Ab initio investigation of the vibronic spectrum involving the two lowest-lying electronic states of HCCO Potential energy surfaces for the electronic states of the HCCS radical correlating at linear nuclear arrangement with the X 2 ⌸ state are calculated by means of an extensive ab initio approach. Particular attention is paid to calculating accurate three-dimensional potential surfaces involving variations of two bending and torsional coordinates, which play the central role in vibronic interactions ͑Renner-Teller effect͒, determining the structure of spectra of this radical. In the second part of this paper we use these potential surfaces and the ab initio computed spin-orbit coupling constant to calculate vibronic spectra of HCCS and DCCS in the framework of a theoretical model developed in our laboratory. The results of the present study are in excellent agreement with those derived by Tang and Saito ͓J. Chem. Phys. 105, 8020 ͑1996͔͒ and thus strongly support the interpretation of their experimental findings.

An ab initio model for handling the Renner–Teller effect in tetra-atomic molecules. I. Introduction of coordinates and the Hamiltonian

“…in the harmonic approximation as square root of a quartic-order expression. That means that this quantity (and consequently also the adiabatic potentials V + , V À ), contrary to the mean adiabatic potential (V + + V À )/2, cannot in general be reliably expressed by an expansion of the type (38). This result is verified in our next study [48].…”

An ab initio model for handling the Renner–Teller effect in tetra-atomic molecules. II. Study of the crossing of potential surfaces

“…Technical details concerning the ab initio calculation of these potential surfaces are given in Ref. [11]; we present here only a brief summary. The electronic configuration of this state with a linear equilibrium geometry is .…”

Perturbative Handling of the Renner–Teller Effect and Spin–Orbit Coupling in Π Electronic States of Triatomic and Tetra-atomic Molecules

“…The range of its applicability has continuously been extended so that it enables us now to tackle also the spin-orbit and magnetic hyperfine effects (24)(25)(26), as well as large-amplitude bending vibrations (27,28). It has been employed to calculate vibronic spectra of several species in and electronic states, e.g., C 2 H + 2 (23,24), (25,26,29), HCCO (28), and HCCS (30). However, the availability of such program packages for ab initio handling of the problem considered does not call into question the usefulness of perturbative approaches for interpretation of a usually very restricted sample of experimental findings.…”