Semiclassical tunneling splittings from short time dynamics: Herman-Kluk-propagation and harmonic inversion.
We investigate a recently proposed method [J. Chem. Phys. 108, 9206 (1998)] to obtain tunneling splittings from short time cross-correlation matrices that were propagated according to the semiclassical propagator of Herman and Kluk. The energy levels were extracted by harmonic inversion of the cross-correlation matrix using the filter diagonalization technique. The aim of this study is twofold: First, the short time behavior of the Herman-Kluk-propagator and the meaning of using cross-correlation matrices rather than autocorrelation functions is addressed. Numerical examples are given for one- and two-dimensional model potentials. Second, the performance of the method is investigated for a system with considerable anharmonicity and coupling. Here the proton transfer in 3,7-dichlorotropolone is considered using an ab initio reaction surface Hamiltonian approach. For this example also the extension to more dimensions is critically discussed.
Institut fur Chemie, Physikalische und Theoretische Chemie, Freie Universitat Berlin, Takustr. 3, D-14195 Berlin, Germany.
Kai
K
Giese
Oliver
O
Kuhn