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Large Amplitude Quantum Mechanics in Polyatomic Hydrides:I. A Particles-on-a-Sphere Model for XH^dn.



M Deskevich, David Nesbitt


A framework is presented for converged quantum mechanical calculations on large amplitude dynamics in polyatomic hydrides (XHn), based on a relatively simple but computationally tractable particles-on-a-sphere (POS) model for the intramolecular motion of the light atoms. The modle assumes independent 2D angular motion of H atoms imbedded on the surface of a sphere with an arbitrary interatomic angular potential, which permits systematic evolution from free rotor to funneling to quasi'rigid polyatomic molecule behavior for small but finite values of total angular momentum J. This work focuses on simple triatom (n=2) and tetratom (n=3) systems as a function of interatomic potential stiffness, with explicit consideration of Hd2^o, NH3, and Hd3O^+ as limiting test cases. The particles on a sphere model also establishes the necessary mathematical groundwork for calculations on dynamically much more challenging XH2, species with n greater than 3, (e.g., models of CHd5^+), where such a reduced dimensionally approach offers prospects for being both quantitatively reliable and yet quantum mechanically tractable, at least for low J values (i.e.,J =0,1,2) characateristic of supersonic jet expansion conditions.
Journal of Chemical Physics


hydrides, large amplitude motion, multidimensional quantum mechanics, rovibrational spectroscopy


Deskevich, M. and Nesbitt, D. (2005), Large Amplitude Quantum Mechanics in Polyatomic Hydrides:I. A Particles-on-a-Sphere Model for XH^dn., Journal of Chemical Physics (Accessed May 22, 2024)


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Created July 31, 2005, Updated October 12, 2021