Elsevier Science Home
Computer Physics Communications Program Library
Full text online from Science Direct
Programs in Physics & Physical Chemistry
CPC Home

[Licence| Download | New Version Template] aagp_v1_0.gz(29 Kbytes)
Manuscript Title: Program for evaluation of non-exchange type integrals required in electron-atom scattering theory using Slater-type orbitals as basis functions.
Authors: R.L. Smith, D.G. Truhlar
Program title: NETI
Catalogue identifier: AAGP_v1_0
Distribution format: gz
Journal reference: Comput. Phys. Commun. 5(1973)80
Programming language: Fortran.
Computer: CDC 6600.
Operating system: SCOPE.
RAM: 10K words
Word size: 60
Keywords: Atomic physics, Integrals, Continuum wave functions, Electron-atom, Variational method, Spherical Bessel functions, Numerical quadrature, Summation of series, Born approximation, Amplitude, X-ray form factor, Factor, Two-center Coulomb integrals.
Classification: 2.7.

Revision history:
Type Tit le Reference
correction 000ACORRECTION 19/07/74 See below
adaptation 0001 NETI/ETI See below

Nature of problem:
The problem of electron scattering from atoms and other quantum mechanical scattering problems can be solved using algebraic variational methods. This program computes the five basic integrals in terms of which all the nonexchange-type integrals which are needed for the scattering calculation can be expressed.

Solution method:
The integrals are evaluated using the procedures of Lyons and Nesbet. We believe these procedures are the fastest methods which can be used to obtain the desired accuracy. In some cases alternative subroutines are provided which use the methods suggested by Bottcher.

Restrictions:
We use the notation of Lyons and Nesbet in the following. For the method used, the parameters lambda, mu, p and q must be non-negative integers, the real parts of alpha and beta must be non-negative, and k1 and k2 must be non-negative and real. Also in our programs, alpha, beta must be real except in the G integral.

Unusual features:
Parameters are included in the program which will allow a user to try different methods of solutions or different accuracy for the G and/or I integrals to achieve a faster possible running time for a given accuracy for a given problem.

Running time:
Typical running times (CPU time) per integral for machine accuracy are: G, 0.0005 s; H, 0.07 s; I, 0.02 s; V, 0.3s; W, 0.005 s. These times are strong functions of the particular parameter values for each integral. The test run requires 6 s (excluding compilation and loading).

CORRECTION SUMMARY
Manuscript Title: Program for evaluation of non-exchange type integrals required in electron-atom scattering theory using Slater-type orbitals as basis functions. (C.P.C. 5(1973)80).
Authors: R.L. Smith, D.G. Truhlar
Program title: 000ACORRECTION 19/07/74
Catalogue identifier: AAGP_v1_0
Distribution format: gz
Journal reference: Comput. Phys. Commun. 8(1974)333
Classification: 2.7.

ADAPTATION SUMMARY
Manuscript Title: Continuum exchange integrals for algebraic variational calculations of electron-atom scattering using Slater-type orbitals as basis functions.
Authors: J. Abdallah Jr., D.G. Truhlar
Program title: 0001 NETI/ETI
Catalogue identifier: AAGP_v1_0
Distribution format: gz
Journal reference: Comput. Phys. Commun. 9(1975)327
Programming language: Fortran.
Computer: CDC CYBER 74.
Operating system: KRONOS 2.1.
RAM: 14K words
Word size: 60
Classification: 2.7.

Nature of problem:
The problem of electron scattering from atoms can be solved using algebraic variational methods. The program NETI computes the nonexchange integrals and the present adaptation NETI/ETI adds the facility to compute the two-electron free-free exchange integrals which are needed for algebraic variational scattering calculations including exchange when exponential-type functions and regular spherical Bessel functions are used as basis functions. The adapted program can be used to evaluate all the integrals needed for electron-atom scattering calculations by the standard algebraic variational methods using exponential-type functions and regular spherical Bessel functions as basis functions.

Solution method:
The exchange integrals are evaluated using the procedures of Lyons and Nesbet with an improvement discussed in this article. In each case the subprogram XLN considers six available methods of computation and choses the optimum one for the integral. The adaptation NET/ETI uses sub- programs of the previously published NETI package for parts of the calculations of the exchange integrals.

Restrictions:
In the notation of Lyons and Nesbet, the program is restricted to non- negative integer values of lambda, mu, p and q while k1,k2, alpha and beta must be real and positive.