  We calculated the total energy of a semiconductor quantum dot which is
defined by the trench gate method. In our calculation we used a recently
developed energy functional called ``orbital-free energy functional". We
compared the total energies obtained by Thomas-Fermi approximation,
orbital-free energy functional and standard local-density approximation for the
square quantum slab geometry. We have seen that this newly developed energy
functional is numerically very efficient, superior to the Thomas-Fermi
approximation and is in good agreement with the local-density approximation for
two different sizes of quantum dot systems.
