  We report a series of calculations testing the predictions of the Tran-Blaha
functional for the electronic structure and magnetic properties of condensed
systems. We find a general improvement in the properties of semiconducting and
insulating systems, relative to calculations with standard generalized gradient
approximations, although this is not always by the same mechanism as other
approaches such as the quasiparticle GW method. In ZnO the valence bands are
narrowed and the band gap is increased to a value in much better agreement with
experiment. The Zn $d$ states do not move to higher binding energy as they do
in LDA+U calculations. The functional is effective for systems with hydride
anions, where correcting self-interaction errors in the 1$s$ state is
important. Similarly, it correctly opens semiconducting gaps in the alkaline
earth hexaborides.It correctly stabilizes an antiferromagnetic insulating
ground state for the undoped cuprate parent CaCuO$_2$, but seriously degrades
the agreement with experiment for ferromagnetic Gd relative to the standard
local spin density approximation and generalized gradient approximations. This
is due to positioning of the minority spin $4f$ states at too low an energy.
Conversly, the position of the La $4f$ conduction bands of La$_2$O$_3$ is in
reasonable accord with experiment as it is with standard functionals. The
functional narrows the Fe $d$ bands of the parent compound LaFeAsO of the iron
high temperature superconductors, while maintaining the high Fe spectral weight
near the Fermi energy.
