Accurate vibrational energy levels of the simplest Criegee intermediate (CH2OO) were determined on a recently developed ab initio based nine-dimensional potential energy surface using three quantum mechanical methods. the first is the iterative Lanczos method using a conventional basis expansion with an exact Hamiltonian. the second and more efficient method is the multi-configurational time-dependent Hartree (MCTDH) method in which the potential energy surface is refit to conform to the sums-of-products requirement of MCTDH. Finally, the energy levels were computed with a vibrational self-consistent field/virtual configuration interaction method in MULTIMODE. the low-lying levels obtained from the three methods are found to be within a few wave numbers of each other, although some larger discrepancies exist at higher levels. the calculated vibrational levels are very well represented by an anharmonic effective Hamiltonian.
H. Yu et al., "Vibrational Energy Levels of the Simplest Criegee Intermediate (CH2OO) from Full-dimensional Lanczos, MCTDH, and MULTIMODE Calculations," Journal of Chemical Physics, vol. 143, no. 8, American Institute of Physics (AIP), Aug 2015.
The definitive version is available at https://doi.org/10.1063/1.4929707
Center for High Performance Computing Research
Keywords and Phrases
Calculations; Hamiltonians; Molecular physics; Potential energy; Potential energy surfaces; Quantum chemistry; Quantum theory; Vibrations (mechanical); Configuration interaction method; Criegee intermediates; Effective Hamiltonian; Iterative Lanczos method; Multimode calculations; Quantum mechanical method; Self-consistent field; Vibrational energy levels; Iterative methods
International Standard Serial Number (ISSN)
Article - Journal
© 2015 American Institute of Physics (AIP), All rights reserved.