GTOBAS: fitting continuum functions with Gaussian-type orbitals. A. Faure, J.D. Gorfinkiel, L.A. Morgan, J. Tennyson.

PROGRAM SUMMARY
Title of program: GTOBAS
Catalogue identifier: ADPV
Ref. in CPC: 144(2002)224
Distribution format: tar gzip file
Operating system: Digital UNIX V5.0, IBM AIX 4.3.2.0
High speed store required: .25MK words
Number of bits in a word: 32
Number of lines in distributed program, including test data, etc: 1127
Keywords: Gaussian basis sets, Bessel and Coulomb functions, R-matrix calculations, Atomic physics, Electron scattering, Molecular physics.
Programming language used: Fortran
Computer: Compaq Alpha-DEC , IBM RS/6000 .

CPC Program Library subprograms used:

 Cat. Id.  Title                             Ref. in CPC
 ADPW      NUMCBAS                            144(2002)224                   
 

Nature of physical problem:
Optimising GTO basis sets to represent continuum functions.

Method of solution:
Numerical continuum functions are read from an external file and the GTOs set is optimised using the method proposed by Nestmann and Peyerimhoff [1].

Restrictions:
The limitation for obtaining satisfactory fits is linked to the intrinsic difficulty of representing a large number of nodes with nodeless Gaussian functions expanded about a single centre.

Typical running time:
1 to 10 minutes (depending on the number of needed GTOs) plus the time taken by the subroutine used to generate the numerical functions.

Unusual features:
The program makes use of subroutines from Numerical Recipes [2]. We also append a module, NUMCBAS, for generating Bessel and Coulomb functions (this paper).

References:

 [1] B.M. Nestmann and S. Peyerimhoff, J. Phys. B: At. Mol. Opt. Phys.   
     23 (1990) L773.                                                     
 [2] W.H. Press, B.P. Flannery, S.A. Teukolsky and W.T. Vetterling,      
     Numerical Recipes in Fortran (Cambridge University Press, 1995).