Self-consistent calculation of the internal strain parameter of silicon

We have extended our total-energy computation method, based on the density-functional formalism in the local-density approximation and written in terms of the Wannier functions of the semiconductor, to include distorted crystals. In this way the internal strain parameter $\xi$ of silicon can be calculated in a self-consistent fashion. The result $\xi =0.86\mathrm{}$ is consistent with the recently reported experimental value (0.73 ±0.03).