Accurate electronic structure calculations are becoming m
ore and more impor-
tant because of the increasing need for information about sy
stems which are hard
to perform experiments on. Databases compiled from theoret
ical results are also
being used more than ever for applications, and the reliabil
ity of the theoretical
methods are of utmost importance. In this thesis, the presen
t limits on theoretical
alloy calculations are investigated and improvements on th
e methods are presented.