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Manuscript Title: A program to test basis sets for quantum calculations with the option to include effective core potentials.
Authors: L.F. Pacios
Program title: INTAMON
Catalogue identifier: ACBO_v1_0
Distribution format: gz
Journal reference: Comput. Phys. Commun. 67(1991)309
Programming language: Fortran.
Computer: IBM COMPATIBLE PC.
Operating system: MSDOS-3.3.
RAM: 55K words
Word size: 32
Keywords: Molecular physics, Atomic basis sets, Effective core Potentials, One-electron, Integrals, Atomic charges.
Classification: 16.10.

Nature of problem:
Orbital atomic kinetic and nuclear attraction energies, <r**m> values m= -2,-1,1,2,3, and integrated charges over selected radial intervals, may serve as useful information on the quality of a given basis set, especially when compared to the corresponding values calculated for the extended Clementi-Roetti atomic functions. This program computes these and other properties for STO or GTO basis functions. An Effective Core Potential (ECP) to represent the atomic core and carry out valence-only ab initio calculations may be also considered and test thus the various basis sets available in the literature.

Solution method:
All the integrals needed to determine the above properties may be expressed in the form of linear expansions of simple terms which include the gamma function. Since ab initio ECPs are analytically fitted to STO- or GTO-type functions, the integrals arising from such potentials share the same form. Integrated charges are numerically calculated with an iterative algorithm based on a mixed use of trapezoidal and Simpson rules until a desired accuracy is reached. The program provides all the information in a very simple way so that it is easy to implement on any personal computer.

Restrictions:
l quantum numbers <=3, n quantum numbers <=6,
Maximum l in ECP operators: 5
Maximum number of orbitals: 15
Maximum number of functions in every orbital expansion: 25
ibid. in every ECP analytical expansion: 30

Unusual features:
None

Running time:
The only time-consuming step is the calculation of charges. For the first test run included (all electron STO Clementi-Roetti basis, two charges) the program requires a total time of 43 seconds in a PC-386 with 80387 math coprocessor. The same case with only one charge requires 17 seconds and with no charges, 6 seconds. The second test (GTO valence-only ECP case) runs seconds in 2 seconds with no charges and requires 4 seconds if two charges are calculated.