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Manuscript Title: Electron scattering by closed shell diatomic molecules.
Authors: A.L. Sinfailam
Program title: ELECTRON-MOLECULE SCATTERING
Catalogue identifier: ACQO_v1_0
Distribution format: gz
Journal reference: Comput. Phys. Commun. 1(1970)445
Programming language: Fortran.
Computer: CDC 3600.
Operating system: PRESTO.
Program overlaid: yes
RAM: 32K words
Word size: 48
Keywords: Quantum chemistry, Electron scattering, Diatomic molecule, Closed shell orbitals, Born-oppenheimer approximation, Single centre expansion, K-matrix eigenphases, Cross section, Schrodinger equation, Continuum hartree fock.
Classification: 16.5.

Other versions:
Cat Id Title Reference
ACZS_v1_0 ELECTRON MOLECULE SCATTERING CPC 20(1980)275

Nature of problem:
A general computer code for studying the low energy electron scattering by closed shell diatomic molecule is presented. It is assumed that the molecule is constrained in its electronic state and does not vibrate or rotate during the collision. The K-matrix elements, the eigenphases and the elastic cross section are evaluted.

Solution method:
Our approach is based on a single centre expansion of the molecular and incident electron orbitals about the centre of mass of the molecule. The target molecule is represented by the Hartree-Fock molecular wave function. The adiabatic of Born-Oppenheimer approximation, which assumes that the molecular axis does not rotate during the collision, is used to describe the scattering process. The coupled integro- differential equations are solved using the method already discussed for electron atom collisions.

Restrictions:
The program is designed to study the scattering by a closed shell diatomic molecule with sigma and pi orbitals. It can, however, be modified to treat higher orbitals and also to examine the scattering by a closed shell diatomic positive molecular ion. Moreover, the code can easily be adapted for the study of positron scattering by a linear molecule. The user must provide the molecular orbitals and the static potentials; these can be evaluated using, for example, the program of Faisal et al.

Running time:
Running time is proportional to N**2, where N is the number of coupled equations. In the 2piu e- -N2 test case, N=20 and the running time is 4 min. Compilation time is 3 min. These figures are for the CDC 3600 at the University of California at San Diego.