  Ab-initio, self-consistent electronic energy bands of rutile TiO2 are
reported within the local density functional approximation (LDA). Our first
principle, non-relativistic and ground state calculations employed a local
density functional approximation (LDA) potential and the linear combination of
atomic orbitals (LCAO). Within the framework of the Bagayoko, Zhao, and
Williams (BZW) method, we solved self-consistently both the Kohn-Sham equation
and the equation giving the ground state charge density in terms of the wave
functions of the occupied states. Our calculated band structure shows that
there is significant O2p-Ti3d hybridization in the valence bands. These bands
are well separated from the conduction bands by an indirect band gap of 2.95
eV, from {\Gamma} to R. Consequently, this work predicts that rutile TiO2 is an
indirect band gap material, as all other gaps from our calculations are larger
than 2.95 eV. We found a slightly larger, direct band gap of 3.05 eV, at the
{\Gamma} point, in excellent agreement with experiment. Our calculations
reproduced the peaks in the measured conduction and valence bands densities of
states, within experimental uncertainties. We also calculated electron
effective mass. Our structural optimization led to lattice parameters of 4.65
{\AA} and 2.97 {\AA} for a_{0} and c_{0}, respectively with a u parameter of
0.3051 and a bulk modulus of 215 GPa.
