Page 38 - Strategies and Applications in Quantum Chemistry From Molecular Astrophysics to Molecular Engineer

THEORY OF ORBITAL OPTIMIZATION IN SCF AND MCSF CALCULATIONS 23

with

The eq.(12) is similar to the eq.(l) in the sense that it requires a compensation
between T and -Z/r. The main difference comes from the presence of and that
might reduce the range of that compensation. In order to solve the eq.(12) one writes
and in the form :

We now study the dependence of the solution of the eq.(14) using the following
scheme :

- we first determine normalised by using some standard program of Quantum
Chemistry ;
- using these normalised we determine the functions and ;

- then we set up the equation :

where f is an unknown function, e is a variable parameter, and are the func-
tions evaluated at the preceding step using the normalised and f (0),
are the values of f and at the origin (note that f (0) is unknown).