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.



Research Center/Lab(s)

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)


Document Type

Article - Journal

Document Version

Final Version

File Type





© 2015 American Institute of Physics (AIP), All rights reserved.

Publication Date

01 Aug 2015