Empirical potential energy surface for Ar⋅SH/D and Kr⋅SH/D

Abstract

High resolution electronic spectroscopy and an empirical potential energy surface for NeSH/D J. Chem. Phys. 110, 5065 (1999); 10.1063/1.478395High resolution electronic spectroscopy of KrOH/D and an empirical potential energy surface Experimental data from vibrationally and rotationally resolved laser induced fluorescence experiments have been used to produce potential energy surfaces ͑PES͒ for the excited à 2 ⌺ ϩ states of the Ar•SH and Kr•SH van der Waals complexes. This was done using a potential energy functional form first suggested by Bowman and co-workers ͓J. Phys. Chem. 94, 2226, 8858 ͑1990͒; Chem. Phys. Lett. 189, 487 ͑1992͔͒ for Ar•OH/D. A discrete variable representation ͑DVR͒ of the vibration-rotation Hamiltonian was used in combination with the implicitly restarted Lanczos method and sequential diagonalization truncation ͑SDT͒ of the DVR Hamiltonian. This approach takes advantage of the sparseness of the DVR Hamiltonian and the reduced order of the SDT representation. This combination of methods greatly reduces the amount of computational time needed to determine the eigenvalues of interest. This is important for the determination of the PES that results from minimizing the difference between the experimental and theoretically predicted values for the vibronic energy levels and their corresponding rotational constants. In addition this procedure was helpful in assigning the absolute vibrational quantum numbers for the deuterated species for which less experimental data was available. Plots of the calculated wavefunctions corresponding to various experimentally vibronic bands indicate that these states sample regions of the PES from 0 degrees, where the hydrogen atom is closest to the rare gas atom, to approximately the saddle point, near the T-shaped configuration. As a result this region of the surface is determined accurately whereas the region of the PES around 180 degrees, corresponding to the sulfur atom being closest to the rare gas atom, is determined only qualitatively.

Ab initio potential energy surfaces, bound states, and electronic spectrum of the Ar–SH complex

“…Also shown is an experimental spectrum from Ref. 20. The spacings between the peaks in the calculated Ar-SH spectrum are consistently ϳ5% smaller than in experiment.…”

“…It is known that the presence of the Ar atom blocks the electronic predissociation of the SH radical, leading to a greatly increased lifetime of up to 600 ns for low-lying bound levels, compared to ϳ1 ns for the uncomplexed species. 20,50 However, the actual lifetime depends on the degree of vibrational excitation, and lifetimes specific to particular levels have been calculated by McCoy. 50 The top panel of Fig.…”

“…Subsequently this group developed empirical PESs for the complex, for both the A state 20 and the X state, 21 by fitting model functions to reproduce laser-induced fluorescence results. The region of the A state PES corresponding to the Ar-S-H configuration ͑Jacobi angles between ϳ90°and 180°͒ was determined only approximately, because the fluorescence experiments did not probe this zone.…”

Computation of Rovibrational Eigenvalues of van der Waals Molecules on a CRAY T3D

“…This technique was first introduced by Pendergast et al [21] in the 2D surface eigenfunction calculations needed by the APH hyperspherical coordinate approach by Parker and Pack [22]. Recently Korambath et al [13] have found that this implicit SDT transformation to be effective for rovibrational eigen problems using sequential computers and Wu and Hayes [23] have applied the implicit SDT technique to obtain the HO 2 rovibrational energy levels on a CRAY T3D.…”

“…Van der Waals molecules have received a good deal of attention recently because of the wealth of high resolution spectroscopic and dynamical data that is becoming available for these weakly bonded molecules [7][8][9][10][11][12]. Previously we reported rovibrational energy calculation using serial algorithms for van der Waals molecule such as Ar-HS, Kr-HS [13], Ar-HCl, and Ar-HO [14]. The Ar-HO molecule was selected for this study to generate detailed performance information that is typical for these atom-diatom van der Waals molecules.…”