# ROTATIONAL SPECTRA AND AB INITIO POTENTIAL ENERGY SURFACE OF THE $H_{2}-OCS$ VAN DER WAALS COMPLEX

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 dc.creator Higgins, Kelly J. en_US dc.creator Yu, Zhenhong en_US dc.creator Klemperer, William en_US dc.date.accessioned 2006-06-15T20:22:05Z dc.date.available 2006-06-15T20:22:05Z dc.date.issued 2002 en_US dc.identifier 2002-RA-02 en_US dc.identifier.uri http://hdl.handle.net/1811/20431 dc.description $^{a}$Jian Tang and A. R. W. McKellar, J. Chem. Phys. 116, 646 (2002). $^{b}$Kelly Higgins and William Klemperer, J. Chem. Phys. 103, 1138 (1999). $^{c}$N. F. Ramsey, Molecular beam (Oxford University, London, 1953). en_US dc.description Author Institution: Department of Chemistry, University of Minnesota; Department of Chemistry and Chemical Biology, Harvard University en_US dc.description.abstract The four-dimensional intermolecular potential energy surface for the $H_{2}-OCS$ complex was obtained at the MP4 level. The potential gives a T-shaped global minimum with a distance of 3.2 {\AA} between $H_{2}$ and OCS, in which $H_{2}$ is nearly parallel to OCS. Bound state calculations of $paraH_{2}-OCS$ give predicted rotational constants of $A = 22652, B = 5994$, and $C = 4611$ MHz, in good agreement with the measured results from high-resolution infrared $studies.^{a}$ The calculated binding energy of $paraH_{2}-OCS$ is $75 cm^{-1}$, almost four times greater than that of $He-OCS.^{b}$ Preliminary bound state calculations of $orthoH_{2}-OCS$ predict binding energies of $99 cm^{-1}$ for the $\Sigma$ state and $64 cm^{-1}$ for the $\Pi$ state. a-type rotational transitions of two isotopomers of the $orthoH_{2}-OCS$ complex were observed between 9 to 31 GHz. The spectral constants of $orthoH_{2}-OC^{32}S$ are $(B+C)/2 = 5113.372(23)$, $(B-C)/2 = 580.337(40)$, and $D_{J} = 2.118(2)$ MHz. The observed $1_{01}-0_{00}$ transition is very close to the expectation of $paraH_{2}-OCS$. This shows that the ground state of the complex is a $\Sigma$ bound state with the T-shaped geometry. The $H_{2}$ nuclear spin dipole-dipole coupling constant $d_{HH}^{c}$ is $14.4(1)$ kHz which indicates a zero-point energy averaged angle of $45^{\circ}$ of $H_{2}$ with respect to the molecular a axis. Preliminary spectra of $D_{2}$-OCS show the existence of both $orthoD_{2}-OCS$ and $paraD_{2}-OCS$ complexes. en_US dc.format.extent 304867 bytes dc.format.mimetype image/jpeg dc.language.iso English en_US dc.publisher Ohio State University en_US dc.title ROTATIONAL SPECTRA AND AB INITIO POTENTIAL ENERGY SURFACE OF THE $H_{2}-OCS$ VAN DER WAALS COMPLEX en_US dc.type article en_US