Abstract
Among the mathematical models used to represent the electronic structure of microscopic systems one of the most valuable is the Hartree-Fock model. The major problem to be solved in this model is the choice of the mathematical functions to be used to represent the Hartree-Fock orbitals. One of the most important suggestions for the Hartree-Fock method was formalized by J.J. Roothaan by way of the technique that was popularized as the method of linear combination of atomic orbitals or base functions. In other words, atomic and molecular orbitals can be obtained as linear combinations of base functions. Although the Hartree-Fock-Roothaan model has become computationally attractive, it is necessary to impose the solution of some technical issues such as:
- which mathematical functions could be used as the base sets? and
- how the base functions should be used to adequately represent the system under study?
The issues related to the alternatives used to answer these two questions will be detailed below.
Keywords
base functions, hydrogenoid base functions, Slater functions, Gaussian functions, Hellmann-Feynman theorem
Authors
Nelson Henrique Morgon
Rogério Custódio
Universidade Estadual de Campinas, Instituto de Química
Translated by
João C. de Andrade
Revised by
Carol H. Collins
