is applied. In the following, the individual terms and their
parametrization are explained in short; details can be taken from the given
literature.
The ligand field is put up in the framework of
the Angular Overlap Model which is further described in
section B.1. For each ligand, the user supplies the
AOM parameters 
, 
and 
(eventually
and 
) as well as the spatial oriention
in form of Eulerian angles 
, 
and (optional) 
or
as a cartesian coordinate triple (x, y, z).
The angle is relevant only in case of anisotropic
-interaction ( 
), if required, it can be
calculated by the program through a plane to be supplied by the
user. Particularly in square planar complexes, the energetic effect
of a mixing in of the (n+1)s orbital becomes important and can be
covered through a parameter 
(see page
). In chelate ligands with conjugated
-electron system, the possibility exists to allow for the phase
coupling between the orbitals of the coordinating atoms of the
chelate; the AOM model then works with two parameters,
und 
(p.).
The operator of electron
repulsion is modeled through Racah parameters A, B and C.
The lowering of d electron interaction which is a consequence of
electron delocalization in the complex that generally occurs to a
different extent in the individual d orbitals, can be allowed for
through orbital reduction factors 
. The general
electron repulsion matrix element then takes the form 
(see [4, 9]).
The spin-orbit coupling operator
has the form 
with the
parameter 
. Spatial anisotropy of orbital momentum is
introduced by the ansatz 
, 
and 
with parameters 
.[2]
An external magnetic field is
described by the operator 
. Here, too, anisotropy can be accounted
for through parameters .
The Trees correction is
a two-electron correction of the form 
(see
[5] and [1]) with the Trees parameter
.