WATERWAVES: wave particles dynamics on a complex triatomic potential

Abstract

The WATERWAVES program suite performs complex scattering calculations by propagating a wave packet in a complex, full-dimensional potential for non-rotating ( J = 0 ) but vibrating triatomic molecules. Potential energy and decay probability surfaces must be provided. Expectation values of geometric quantities can be calculated, which are useful for following the wave packet motion. The programs use a local complex potential approximation (LCP) for the Hamiltonian and Jacobi coordinates. The bottleneck of the calculation is the application of each term of the Hamiltonian to the wave packet. To solve this problem the programs use a different representation for each term: normalized associated Legendre polynomials P j K ( x ) as a functional basis for the angular kinetic term and an evenly spaced grid for the radial kinetic term yielding a fully point-wise representation of the wave functions. The potential term is treated using an efficient Discrete Variable Representation (DVR) being diagonal in the coordinate representation. The radial kinetic term uses a fast Fourier transform (FFT) to obtain an operator which is diagonal in the momentum space. To avoid artificial reflection at the boundaries of the grid a complex absorbing potential is included for calculating continuum quantities. Asymptotic analysis is performed to obtain scattering observables such as cross sections and other dynamical properties. Program summary Program title: WATERWAVES Catalogue identifier:ADXT_v1_0 Program summary URL: http://cpc.cs.qub.ac.uk/summaries/ADXT_v1_0 Program obtainable from: CPC Program Library, Queen's University of Belfast, N. Ireland Licensing provisions: Freely available from CPC Programming language: Fortran 77 Computer(s) for which the program has been designed: PC Operating system(s) for which the program has been designed: Linux RAM required to execute with typical data: case dependent: test run requires 976 024 kB No. of bytes in distributed program, including test data, etc.:11 262 681 No. of lines in distributed program, including test data, etc.:2 510 113 Distribution format:tar.gz Number of processors used: 1 External routines/libraries used: None CPC Program Library subprograms used: None Nature of problem: The WATERWAVES program suite performs complex scattering calculations for calculating the nuclear dynamics subsequent to excitation by, for example, electron or photon impact and leading to dissociative attachment or vibrational excitation. This program treats in a fully multidimensional way the nuclear motion based on the use of complex potential surfaces of three-atom systems. Complex potential energy surfaces have to be provided from fixed-nuclei calculations. Solution method: By propagating a wave packet in a complex, full-dimensional potential for non-rotating ( J = 0 ) but vibrating triatomic molecules, expectation values of geometric quantities can be calculated, which are useful for following the wave packet motion. The programs use a local complex potential approximation (LCP) for the Hamiltonian and Jacobi coordinates. Potential energy and decay probability surfaces must be provided. To solve this problem the programs use a different representation for each term. To avoid artificial reflection at the boundaries of the grid a complex absorbing potential is included for calculating continuum quantities. Asymptotic analysis is performed to obtain scattering observables such as cross sections and other dynamical properties. Additional comments: Program asymptot.f for analysing results, test data and shell scripts to make a movie of the results. Running time: Case dependent: test run requires about 200 minutes on a 3.00 GHz Intel Pentium 4 machine provided with 2 060 044 kB of memory.