Programs in Physics & Physical Chemistry
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|Manuscript Title: IMPACT: a program for the solution of the coupled integro- differential equations of electron-atom collision theory.|
|Authors: M.A. Crees, M.J. Seaton, P.M.H. Wilson|
|Program title: IMPACT|
|Catalogue identifier: ACYE_v1_0|
Distribution format: gz
|Journal reference: Comput. Phys. Commun. 15(1978)23|
|Programming language: Fortran.|
|Computer: CDC 7600.|
|Operating system: SCOPE 2.1.4.|
|Program overlaid: yes|
|RAM: 20K words|
|Word size: 60|
|Keywords: Atomic physics, Electron-atom, Electron-ion, Scattering.|
Nature of problem:
It is required to obtain approximate solutions of the Schroedinger equation (H-E)Psi=0 where Psi is the wave function for a system containing (M+1)-electrons and a nucleus of charge z. Using a variational principle, one obtains a system of coupled integro- differential (ID) equations for the radial functions F(r) and coefficients c. IMPACT is a computer program for the solution of these equations. Put E = ELOW + EKLSQ where ELOW is the energy for the ground state of the M electron system and EKLSQ is input to the program. For EKLSQ less than 0, IMPACT obtains approximate solutions of the Schroedinger equation for the bound state Psin of the (M+1) electron system with energy EN closest to ELOW + EKLSQ. For EKLSQ greater than 0, IMPACT solves the corresponding electron-atom or electron-ion collision problem.
The radial functions Fi(r) are tabulated at points r = R(1), R(2), ..., R(N), and matched to functions for r> R(N) obtained using a modified version of the program ASYM of Norcross. Using numerical methods, the ID equations are replaced by linear algebraic (LA) equations which are solved using standard techniques.
The program IMPACT is provided in a form which must be pre-processed by a program IMPPRO, which inserts dimensions. Restrictions on the complexity of the problems which can be solved are determined entirely by available machine time and core store.
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