The Developing And Application Of Parallel Algorithm In Quantum Dynamics

For the problem of parallel algorithms of quantum dynamics, GPU algorithm of accelerating modified Shepard interpolated potential energy calculations is developed; the OpenMP and MPI parallel algorithms of bound state calculation of vibrational and rotational spectrum of van der Waals(vdW) system is investigated; the method of seven dimension quantum dynamics theory and MPI/OpenMP parallel algorithms of X+NH3reaction is investigated, and this method and algorithm is applied to study the reaction of Cl (2P)+NH3/ND3. The present thesis is organized as follows:1. The potential energy surfaces constructed with the Modified Shepard interpolation scheme have been widely used in studies of chemical reaction dynamics. The energy of any configuration is obtained by interpolation of ab initio data points. The potential energy surface constructed using this method is high precision, more precise for research of chemical reaction dynamics. However, in practical application, the interpolation potential energy surface is computationally intensive, which limits the application of this method. This work is based on GPU computing power and highly parallel features, development of GPU algorithm of the Shepard interpolation method to calculate the potential energy. The algorithm is veritied through the potential energy surfaces of the three reactions of H+H2O(?)H2+OH, H+NH3(?)H2+NH2, H+CH4(?)H2+CH3. We find that the GPU algorithm has obvious advantages relative CPU algorithm, GPU speedup increases with the system size and speedup inceases with the increase of the number of data points in the PES(Potential Energy Surface).2. The bound state calculation of vibrational and rotational spectrum of vdW system needs exact solution of the Schrodinger equation. Because the wave function of the system is expanded as the product of the basis function of each degree of freedom, so the size of basis set increase exponentially with the number of atoms. Computation time and memory requirements have increased. Computing can be achieved by application of parallel computing. Parallel algorithms of bound state calculation using MPI between nodes and OpenMP in node is developed for the research of linear molecules-linear molecular vibrational and rotational spectrum of vdW system, and the parallel algorithm is verified by using N2O-N2O system, the results show that the computational efficiency is significantly improved, the speedup is1.67times to8.6times.3. That there are deep wells before and after the transition state is a challenge for theoretical calculation of quantum dynamics. In the calculation of dynamics, a seven-dimensional quantum dynamics model for the reaction X+YCZ2is employed. NH2group which does not participate in the reaction remains unchanged during the reaction, the two reactions of Cl+NH3and Cl+ND3are investigated by using this model. The calculated results show that C1+NH3and Cl+ND3have similar dynamic behavior and the reaction probabilities are small, consistent with the experiment observations. Because the reaction Cl+ND3is more complex and the Cl atom has heavy mass, so the size of the total basis function is3.175*109, the number of potential energy nodes is3.78*1010, the entire propagation time is25,000a. u. This is one of the largest computational work of current quantum dynamics study.