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Manuscript Title: EROTVIB: a general program to calculate rotationally and/or
vibrationally elastic and inelastic cross sections for electron
(positron) scattering by spherical, symmetric and asymmetric top
molecules. | ||

Authors: A. Jain, D.G. Thompson | ||

Program title: EROTVIB | ||

Catalogue identifier: AAJM_v1_0Distribution format: gz | ||

Journal reference: Comput. Phys. Commun. 32(1984)367 | ||

Programming language: Fortran. | ||

Computer: CYBER-170/750. | ||

Operating system: NOS 1.4. | ||

RAM: 64K words | ||

Word size: 60 | ||

Keywords: Spherical top, Symmetric top, Asymmetric top, Point group, Excitation vibrational, Rotational excitation, Scattering elastic, Adiabatic-nuclei Rotation (vibration) Approximations, K-matrix, T-matrix, Body-fixed frame, Closure formula, Total, Differential and Moment transfer Cross sections, Scattering, Electron, Molecule. | ||

Classification: 16.5. | ||

Subprograms used: | ||

Cat
Id | Title | Reference |

ACFD_v1_0 | ASYMTOP | CPC 30(1983)301 |

Nature of problem:This program calculates cross sections (total, differential and momentum transfer) for rotationally and/or vibrationally elastic and inelastic scattering of low energy electron (positron) impact by polyatomic molecules. It requires the body-fixed (BF) frame K-matrices for each symmetry (and at each geometry in case of vibrational excitation) as the input. For a polar molecule, the program has the provision to use the closure formula of Crawford and Dalgarno in order to obtain converged cross sections. | ||

Solution method:The BF frame scattering amplitude is first converted into space-fixed (SF) frame and then the Chase formula, in the adiabatic-nuclei-rotation (vibration) approximation, is employed to derive expressions for rotationally and/or vibrationally elastic and/or inelastic cross sections. | ||

Restrictions:The program is designed to accept K-matrices only up to the maximum dimension of 22*22. This, in the context of present molecules, means that up to lmax=7 partial waves can be included in the calculation [ in this case, in eq. (1) LBIG=14]. At the same time, the maximum value of the final rotational quantum number (JF(I)) can be only up to 5. However, for JF(I)>5 and lmax >7, the program can easily be modified by changing dimensions of various arrays (described in the code). | ||

Running time:For the present test case of e-H2O scattering the determination of AL coefficients for LBIG=7 [eq. (1)] takes only 0.2 s. In this calculation, the time to evaluate asymmetric top eigenfunctions is not included; however, this should again be less than one second. |

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