High-accuracY AB-INITIO ROVIBRATIONAL spectroscopy

Gábor Czakó,^a Edit Mátyus,^b Attila G. Császár,^b Bastiaan J. Braams,^a and Joel M. Bowman^a

^a Cherry L. Emerson Center for Scientific Computation and Department of Chemistry, Emory University, Atlanta, GA 30322

^b Laboratory of Molecular Spectroscopy, Institute of Chemistry, Eötvös University, P. O. Box 32, H-1518 Budapest 112, Hungary

The computation of high-accuracy and/or complete rotational-vibrational spectra of small molecules requires the use of the variational techniques for solving the Schrödinger equation of the nuclei. Strategies are introduced which in principle allow the determination of the complete rotational-vibrational spectrum of triatomic molecules [1,2,3,4]. The newly developed program packages are described. These packages have been employed for computing (ro)vibrational energy levels and effective molecular properties, e.g. temperature-dependent effective structures and vibrationally averaged rotational constants, for several molecules, such as H₂O, CO₂, N₂O, CH₂, CCl₂, CHCl, and H₃⁺.

Variational vibrational calculations can also be performed for molecules having more than 3 atoms. General program packages MULTIMODE and the recently developed DEWE [5], discrete variable representation (DVR) of the Eckart–Watson (EW) Hamiltonian with exact inclusion (E) of an arbitrary potential, are introduced. Results obtained by DEWE for linear and nonlinear test cases are presented [5]. Our recent MULTIMODE study on the F^––CH₄ anion complex is also introduced [6]. The vibrational spectrum of F^––CH₄ has been computed employing newly developed global potential energy and dipole moment surfaces.

[1]     G. Czakó, T. Furtenbacher, A. G. Császár, and V. Szalay, Mol. Phys. 102, 2411 (2004).

[2]     G. Czakó, V. Szalay, A. G. Császár, and T. Furtenbacher, J. Chem. Phys. 122, 024101 (2005).

[3]     G. Czakó, V. Szalay, A. G. Császár, J. Chem. Phys. 124, 014110 (2006).

[4]     G. Czakó, T. Furtenbacher, P. Barletta, A. G. Császár, V. Szalay, and B. T. Sutcliffe,      Phys. Chem. Chem. Phys. 9, 3407 (2007).

[5]     E. Mátyus, G. Czakó, B. T. Sutcliffe, and A. G. Császár, J. Chem. Phys. 127, 084102    (2007).

[6]     G. Czakó, B. J. Braams, and J. M. Bowman, J. Phys. Chem. A submitted (2008).

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