A general rigorous quantum dynamics algorithm to calculate vibrational energy levels of pentaatomic molecules |
| |
Authors: | Hua-Gen Yu |
| |
Institution: | Department of Chemistry, Brookhaven National Laboratory, Upton, NY 11973-5000, USA |
| |
Abstract: | An exact variational algorithm is presented for calculating vibrational energy levels of pentaatomic molecules without any dynamical approximation. The quantum mechanical Hamiltonian of the system is expressed in a set of orthogonal coordinates defined by four scattering vectors in the body-fixed frame. The eigenvalue problem is solved using a two-layer Lanczos iterative diagonalization method in a mixed grid/basis set. A direct product potential-optimized discrete variable representation (PO-DVR) basis is used for the radial coordinates while a non-direct product finite basis representation (FBR) is employed for the angular variables. The two-layer Lanczos method requires only the actions of the Hamiltonian operator on the Lanczos vectors, where the potential-vector products are accomplished via a pseudo-spectral transform technique. By using Jacobi, Radau and orthogonal satellite vectors, we have proposed 21 types of orthogonal coordinate systems so that the algorithm is capable of describing most five-atom systems with small and/or large amplitude vibrational motions. Finally, an universal program (PetroVib) has been developed. Its applications to the molecules , and the van der Waals cluster He3Cl2 are also discussed. |
| |
Keywords: | Vibrational spectrum Variational calculation Five-atom molecule Large amplitude motion Methane and van der Waals complex |
本文献已被 ScienceDirect 等数据库收录! |
|