We present calculated electronic properties of gallium nitride (GaN), silicon (Si), diamond (C), and ruthenium dioxide $\left({\mathrm{RuO}}_2\right).\mathrm{}$ We implemented a simple computational procedure that avoids a recently identified basis set and variational effect. This effect, inherent to the use of basis sets in variational calculations, is believed to have affected ab initio calculations of electronic properties of semiconductors since their inception. We employed ab initio, density-functional calculations using a local-density-approximation potential and the linear combination of atomic orbital formalism. There is an excellent agreement between our findings and experimental results. In particular, the calculated, direct, minimum band gap of GaN, for low temperatures, is 3.2 eV, while the practical band gap, as per the calculated density of states, is 3.40 eV. Band gaps and excitation energies for silicon and diamond compare favorably with experimental results.

• Received 10 July 1998

DOI:https://doi.org/10.1103/PhysRevB.60.1563