Quantum Monte Carlo calculations of nanostructure optical gaps: application to silicon quantum dots.
Quantum Monte Carlo (QMC) calculations of the optical gaps of silicon quantum dots ranging in size from 0 to 1.5 nm are presented. These QMC results are used to examine the accuracy of density functional (DFT) and empirical pseudopotential based calculations. The GW approximation combined with a solution of the Bethe-Salpeter equation performs well but is limited by its scaling with system size. Optical gaps predicted by DFT vary by 1-2 eV depending on choice of functional. Corrections introduced by the time dependent formalism are found to be minimal in these systems.
Williamson
Andrew J
AJ
Lawrence Livermore Laboratory, Livermore, California 94550, USA.
Grossman
Jeffrey C
JC
Hood
Randolph Q
RQ
Puzder
Aaron
A
Galli
Giulia
G