Fernández Ramos, Antonio2018-06-192018-06-192013-04-04Fernández-Ramos, A. (2013). Accurate treatment of two-dimensional non-separable hindered internal rotors. The Journal Of Chemical Physics, 138, 134112. doi: 10.1063/1.47984070031-9228http://hdl.handle.net/10347/16848The following article appeared in The Journal of Chemical Physics 138, 134112 (2013) and may be found at https://doi.org/10.1063/1.4798407This work presents an accurate way for calculating partition functions of strongly coupled hindered rotors in two dimensions. The two-dimensional torsional potential is generated from electronic structure calculations and fitted to Fourier series. The kinetic energy includes off-diagonal terms which are allowed to vary with the torsional angles, and these terms were also fitted to Fourier series. The resulting Hamiltonian leads to a coupled Schrödinger equation which was solved by the variational method. Therefore, the final two-dimensional non-separable (2D-NS) partition function incorporates coupling terms in both the kinetic and the potential energy. The methodology has been tested for propane, methyl formate, and a hydrogen abstraction transition state from propanone by the OH radical. How to incorporate the 2D-NS partition function in the total vibrational-rotational partition function is also discussedeng© 2013 American Institute of Physics. This article may be downloaded for personal use only. Any other use requires prior permission of the author and AIP Publishingjournal article10.1063/1.47984071945-0699open access