The metal-insulator transition in quasiparticle theory and Kohn-Sham theory

We investigate the pressure-induced metal-insulator transition of silicon in the diamond structure. Quasiparticle theory (QPT) calculations are performed within the GW approximation, and Kohn-Sham theory (KST) results are obtained by using an exchange-correlation potential derived from the GW self-energy operator, not using the common local-density approximation (LDA). In both KST and the LDA, metallization occurs at a much larger volume than in QPT. These results suggest that the metallization point and Fermi surface of the Kohn-Sham electrons are not necessarily those of the real system.