Eur. Phys. J. B 66, 7-15 (2008)
https://doi.org/10.1140/epjb/e2008-00388-1

Application of Lanczos-based time-dependent density-functional theory approach to semiconductor nanoparticle quantum dots

¹ Industrial Research Limited, 69 Gracefield Road, P.O. Box 31-310, 5040 Lower Hutt, New Zealand
² School of Chemical and Physical Sciences, Victoria University of Wellington, P.O. Box 600, 6140 Wellington, New Zealand
³ The Abdus Salam International Centre for Theoretical Physics (ICTP), 34014 Trieste, Italy
⁴ CNR-INFM DEMOCRITOS National Simulation Center, 34014 Trieste, Italy

Corresponding author: ^a b.walker@irl.cri.nz

Received: 27 June 2008
Revised: 30 August 2008
Published online: 18 October 2008

Abstract

We present a density-functional theory study of Si nanoparticle quantum dots, focusing on determination of their optical properties. To calculate the absorption spectra of our quantum dot models we use a recently-developed method based on the application of Lanczos algorithms to linear-response time-dependent density-functional theory (LR-TDDFT). Quantum dot models are obtained by cutting Si atoms from the bulk crystal lattice and adding appropriate H terminating atoms to the surface; these structures are relaxed using density-functional theory in the plane-wave pseudopotential supercell approach, and then absorption spectra are calculated. We verify that with increasing size of the nanoparticle, the optical gap/onset of absorption steadily moves to lower energies. The paper represents an important demonstration of this new methodology on a class of systems that are the focus of significant current research in nanoscience.