There is an increasing interest in taking the orbital degeneracy
into account for a number of systems,
for instance fullerenes and transition metal compounds.
Within auxiliary field QMC, a system with the orbital degeneracy N
is often treated by using 2N(2N-1)/2 Ising fields in a
Hubbard-Stratononvich transformation. We
show how it is possible to instead use one
field which takes N+1 complex values. Alternatively, for a somewhat
larger N we use approximate but accurate transformations with
less than N+1 fields. We also show how one can reduce
the variance by using appropriate transformations.
Back to main page.
Max-Planck Institut für Festkörperforschung
Postfach 800 665
D-70506 Stuttgart