title: The ground state tunneling splitting of malonaldehyde: accurate full dimensional quantum dynamics calculations.
abstract: Benchmark calculations of the tunneling splitting in malonaldehyde using the full dimensional potential proposed by Yagi et al. are reported. Two exact quantum dynamics methods are used: the multiconfigurational time-dependent Hartree (MCTDH) approach and the diffusion Monte Carlo based projection operator imaginary time spectral evolution (POITSE) method. A ground state tunneling splitting of 25.7+/-0.3 cm(-1) is calculated using POITSE. The MCTDH computation yields 25 cm(-1) converged to about 10% accuracy. These rigorous results are used to evaluate the accuracy of approximate dynamical approaches, e.g., the instanton theory.
authors.affiliation: Theoretische Chemie, TU München, Lichtenbergstr. 4, D-85747 Garching, Germany.
authors.forename: Maurício D
authors.initials: MD
authors.lastname: Coutinho-Neto
authors.forename: Alexandra
authors.initials: A
authors.lastname: Viel
authors.forename: Uwe
authors.initials: U
authors.lastname: Manthe