Tunneling splitting in double-proton transfer: Direct diagonalization results for porphycene
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Título: | Tunneling splitting in double-proton transfer: Direct diagonalization results for porphycene |
Autor/a: | Smedarchina, Zorka Siebrand, Willem Fernández-Ramos, Antonio |
Centro/Departamento: | Universidade de Santiago de Compostela. Centro de Investigación en Química Biolóxica e Materiais Moleculares Universidade de Santiago de Compostela. Departamento de Química Física |
Data: | 2014-11-05 |
Editor: | AIP Publishing |
Cita bibliográfica: | Smedarchina, Z., Siebrand, W., & Fernández-Ramos, A. (2014). Tunneling splitting in double-proton transfer: Direct diagonalization results for porphycene. The Journal Of Chemical Physics, 141, 174312. doi: 10.1063/1.4900717 |
Resumo: | Zero-point and excited level splittings due to double-proton tunneling are calculated for porphycene and the results are compared with experiment. The calculation makes use of a multidimensional imaginary-mode Hamiltonian, diagonalized directly by an effective reduction of its dimensionality. Porphycene has a complex potential energy surface with nine stationary configurations that allow a variety of tunneling paths, many of which include classically accessible regions. A symmetry-based approach is used to show that the zero-point level, although located above the cis minimum, corresponds to concerted tunneling along a direct trans − trans path; a corresponding cis − cis path is predicted at higher energy. This supports the conclusion of a previous paper [Z. Smedarchina, W. Siebrand, and A. Fernández-Ramos, J. Chem. Phys. 127, 174513 (2007)] based on the instanton approach to a model Hamiltonian of correlated double-proton transfer. A multidimensional tunneling Hamiltonian is then generated, based on a double-minimum potential along the coordinate of concerted proton motion, which is newly evaluated at the RI-CC2/cc-pVTZ level of theory. To make it suitable for diagonalization, its dimensionality is reduced by treating fast weakly coupled modes in the adiabatic approximation. This results in a coordinate-dependent mass of tunneling, which is included in a unique Hermitian form into the kinetic energy operator. The reduced Hamiltonian contains three symmetric and one antisymmetric mode coupled to the tunneling mode and is diagonalized by a modified Jacobi-Davidson algorithm implemented in the Jadamilu software for sparse matrices. The results are in satisfactory agreement with the observed splitting of the zero-point level and several vibrational fundamentals after a partial reassignment, imposed by recently derived selection rules. They also agree well with instanton calculations based on the same Hamiltonian |
Descrición: | The following article appeared in The Journal of Chemical Physics 141, 174312 (2014) and may be found at https://doi.org/10.1063/1.4900717 |
Versión do editor: | https://doi.org/10.1063/1.4900717 |
URI: | http://hdl.handle.net/10347/16851 |
DOI: | 10.1063/1.4900717 |
ISSN: | 0031-9228 |
E-ISSN: | 1945-0699 |
Dereitos: | © 2014 AIP Publishing LLC. This article may be downloaded for personal use only. Any other use requires prior permission of the author and AIP Publishing |
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