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Partition function for hindered, one-and multi-dimensional rotors

Janakiraman, Deepika and Sebastian, KL (2012) Partition function for hindered, one-and multi-dimensional rotors. In: COMPUTATIONAL AND THEORETICAL CHEMISTRY, 988 . pp. 6-12.

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Official URL: http://dx.doi.org/10.1016/j.comptc.2012.02.019


Writing the hindered rotor (hr) partition function as the trace of (rho) over cap = e(-beta(H) over cap hr), we approximate it by the sum of contributions from a set of points in position space. The contribution of the density matrix from each point is approximated by performing a local harmonic expansion around it. The highlight of this method is that it can be easily extended to multidimensional systems. Local harmonic expansion leads to a breakdown of the method a low temperatures. In order to calculate the partition function at low temperatures, we suggest a matrix multiplication procedure. The results obtained using these methods closely agree with the exact partition function at all temperature ranges. Our method bypasses the evaluation of eigenvalues and eigenfunctions and evaluates the density matrix for internal rotation directly. We also suggest a procedure to account for the antisymmetry of the total wavefunction in the same. (C) 2012 Elsevier B.V. All rights reserved.

Item Type: Journal Article
Additional Information: Copyright for this article belongs to Elsevier Science
Keywords: Hindered rotor;Partition function;Multidimensional rotors;Indistinguishability
Department/Centre: Division of Chemical Sciences > Inorganic & Physical Chemistry
Date Deposited: 22 Aug 2012 05:09
Last Modified: 22 Aug 2012 05:10
URI: http://eprints.iisc.ac.in/id/eprint/44432

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