Electronic properties of realistic anatase TiO2 nanoparticles from G(0)W(0) calculations on a Gaussian and plane waves scheme

Abstract

The electronic properties of realistic (TiO2)n nanoparticles (NPs) with cuboctahedral and bipyramidal morphologies are investigated within the many-body perturbation theory (MBPT) G0W0 approximation using PBE and hybrid PBEx (12.5% Fock contribution) functionals as starting points. The use of a Gaussian and plane waves (GPW) scheme reduces the usual O4 computational time required in this type of calculation close to O3 and thus allows considering explicitly NPs with n up to 165. The analysis of the Kohn-Sham energy orbitals and quasiparticle (QP) energies shows that the optical energy gap (Ogap), the electronic energy gap (Egap), and the exciton binding energy (ΔEex) values decrease with increasing TiO2 NP size, in agreement with previous work. However, while bipyramidal NPs appear to reach the scalable regime already for n = 84, cuboctahedral NPs reach this regime only above n = 151. Relevant correlations are found and reported that will allow one to predict these electronic properties at the G0W0 level in even much larger NPs where these calculations are unaffordable. The present work provides a feasible and practical way to approach the electronic properties of rather large TiO2 NPs and thus constitutes a further step in the study of realistic nanoparticles of semiconducting oxides.