Multigap absorption inCaCu3Ti4O12and the prediction capability ofab initiomethods

Abstract

We report the electronic properties of the quadruple perovskite CaCu 3 Ti 4 O 12 as obtained via several densityfunctional based methods and propose a new interpretation of optical experiments to the effect that four distinct transitions (centered around 0.7, 1.5, 2.5, and 3.5 eV) contribute to the spectrum. The comparison with experiment is satisfactory, especially after we account for the effects of spin disorder, which does not close the fundamental gap but suppresses the transition intensity. We find that some of the methods we employ tend to overestimate considerably the gaps for standard values of the respective adjustable parameters.

Theoretical and experimental investigation of optical absorption anisotropy in β-Ga2O3

“…Confirming recent results on magnetic Mott insulators [32] the best performance in comparison with experiment is that of VPSIC. The technical ingredient were essentially standard [33].…”

“…The level of agreement with the experimental data was generally good, always well within 10% and down to 2% on the absolute values of the gap. Confirming recent results on magnetic Mott insulators [32] the best performance in comparison with experiment is that of VPSIC. The technical ingredients were essentially standard 6 .…”

“…It is also worth mentioning that, as usual in the business of ab initio optical properties, we implicitly identify eigenvalues and eigenvectors of Kohn-Sham equations as quasiparticle energies and states. This is justified by the Kohn-Sham equations being formally identical to Hedin-Lundqvist quasiparticle equations if the self-energy is identified with the exchange-correlation potential or its corrected versions [25,32].…”