Tunneling splittings of vibrationally excited states using general instanton paths
| Autor: | Mihael Eraković, Marko T. Cvitaš |
|---|---|
| Rok vydání: | 2020 |
| Předmět: |
Chemical Physics (physics.chem-ph)
Instanton Water dimer 010304 chemical physics Physics FOS: Physical sciences General Physics and Astronomy Semiclassical physics 010402 general chemistry 01 natural sciences Action (physics) 0104 chemical sciences Chemistry Physics - Chemical Physics Excited state Quantum mechanics 0103 physical sciences instanton theory tunnelling splittings tunnelling dynamics rovibrational states of molecules Physical and Theoretical Chemistry Wave function Quantum tunnelling Curse of dimensionality |
| Zdroj: | Journal of Chemical Physics |
| ISSN: | 1089-7690 0021-9606 |
| DOI: | 10.1063/5.0024210 |
| Popis: | A multidimensional semiclassical method for calculating tunneling splittings in vibrationally excited states of molecules using Cartesian coordinates is developed. It is an extension of the theory by Mil'nikov and Nakamura [$\textit{ J. Chem. Phys.}$ $\textbf{122}$, $124311$ $(2005)$] to asymmetric paths that are necessary for calculating tunneling splitting patterns in multi-well systems, such as water clusters. Additionally, new terms are introduced in the description of the semiclassical wavefunction that drastically improve the splitting estimates for certain systems. The method is based on the instanton theory and builds the semiclassical wavefunction of the vibrationally excited states from the ground-state instanton wavefunction along the minimum action path and its harmonic neighborhood. The splittings of excited states are thus obtained at a negligible added numerical effort. The cost is concentrated, as for the ground-state splittings, in the instanton path optimization and the hessian evaluation along the path. The method can thus be applied without modification to many mid-sized molecules in full dimensionality and in combination with on-the-fly evaluation of electronic potentials. The tests were performed on several model potentials and on the water dimer. Comment: The following article has been submitted to Journal of Chemical Physics. After it is published, it will be found at https://aip.scitation.org/journal/jcp |
| Databáze: | OpenAIRE |
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