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Manuscript Title: Nonreactive atom/molecule-surface scattering within the finite basis
wave packet method. | ||

Authors: D. Lemoine | ||

Program title: FBWPSURF | ||

Catalogue identifier: ADDR_v1_0Distribution format: gz | ||

Journal reference: Comput. Phys. Commun. 97(1996)331 | ||

Programming language: Fortran. | ||

Computer: HP 9000 Series 715. | ||

Operating system: UNIX, UNICOS. | ||

RAM: 1.2M words | ||

Word size: 32 | ||

Keywords: Solid state physics, Molecule-surface, Collision cascade, Diffractive scattering, Rotational excitation, Quantum wave packet, Finite basis, Representation, Pseudospectral scheme, Elastic. | ||

Classification: 7.10, 16.7. | ||

Nature of problem:The scattering matrix and transition probabilities are computed for the nonreactive collisions of closed-shell atoms or diatomic molecules with a rigid surface. The inelastic channels which are considered are the diffractive scattering and the rotational (de-) excitation for a diatomic collider. The surface unit cell has the general form of a parallelogram. One may appropriately reduce the dimensionality by defining either a 1D vs a 2D corrugation or a flat surface. | ||

Solution method:The time-dependent wave function of the collider is expanded in terms of the asymptotic eigenfunctions. The resulting finite basis representation (FBR) consists of a direct product of plane waves for the translational motion and of a nondirect product of spherical harmonics for the angular degrees of freedom [1, 2]. The wave function is propagated in time owing to the Chebychev scheme [3], in the FBR where the kinetic energy operator is diagonal. Potential matrix elements are efficiently evaluated in a pseudospectral way by means of sequential 1D transformtions of the wave function between momentum and coordinate spaces. Fast Fourier transforms are performed for the translational and azimuthal coordinates whereas a Gauss-Legendre transform is used for the polar coordinate. Additionally, FBWPSURF makes use of various techniques: floating grid and adjustable basis [4], efficient cutoff procedure and simplified asymptotic treatment [2]. The initial wave function is chosen to be a Gaussian distribution along the surface normal, corresponding to a range of energies over which a post- collisional analysis can be performed [5]. | ||

Running time:5.5 s (160 s) on a Cray 98 (Silicon Graphics R 4400 Indigo) for the test run. | ||

References: | ||

[1] | G.C. Corey, J.W. Tromp and D. Lemoine, in: Numerical Grid Methods and Their Application to Schrodinger's Equation, edited by C. Cerjan (Kluwer Academic, Dordrecht, 1993) p. 1. | |

[2] | D. Lemoine, J. Chem. Phys. 101(1994)10526. | |

[3] | H. Tal-Ezer and R. Kosloff, J. Chem. Phys. 81(1984)3967. | |

[4] | D. Lemoine and G.C. Corey, J. Chem. Phys. 92(1990)6175. | |

[5] | R.C. Mowrey and D.J. Kouri, Comp. Phys. Commun. 63(1991)100. |

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