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Manuscript Title: A general program to calculate atomic continuum processes using the NIEM method.
Authors: R.J.W. Henry, S.P. Rountree, E.R. Smith
Program title: NIEM POTC1
Catalogue identifier: AAJG_v1_0
Distribution format: gz
Journal reference: Comput. Phys. Commun. 23(1981)233
Programming language: Fortran.
Computer: IBM 3033.
Operating system: JES2.
RAM: 232K words
Word size: 32
Peripherals: disc.
Keywords: Atomic physics, Electron atom Scattering, Electron ion scattering, Noniterative integral Equation method.
Classification: 2.4.

Subprograms used:
Cat Id Title Reference
AAJH_v1_0 NIEM NIES2 CPC 23(1981)233
AAJI_v1_0 NIEM ASYM3 CPC 23(1981)233
ACWN_v1_0 0001 GRN2 CPC 23(1981)233

Nature of problem:
This program calculates all the interaction potentials involving the bound and continuum electrons necessary to enable electron atom or electron ion scattering to be calculated for a general atomic system. The bound orbitals are specified analytically. Direct potentials, the coefficients in the asymptotic expansion of the potentials, exchange coefficients, and correlation potentials are stored on a permanent tape or disc file for use by NIEM NIES2.

Solution method:
The one-electron integrals and the multiple integrals are evaluated numerically using the trapezoidal rule. The triangular relations are used to determine the number of coupled channels given the quantum numbers of the target and scattering states. The angular integrals are carried out using the methods of Racah algebra.

Up to 10 bound orbitals and 6 scattering channels for each total angular momentum can be included. Larger calculations can be made by recompiling with larger dimensions. Instructions on comment cards are given to enable the user to increase the dimensions. Normal output includes the dimension size currently used and the size allocated. LS coupling is assumed.

Running time:
The test run took 12.4 and 42.9 s on the IBM 3033.