Issue 43, 2015

Chemical trends in the optical properties of rocksalt nanoparticles


The nature and magnitude of the optical gaps of rocksalt alkaline earth (MgO, CaO, SrO, MgS, MgSe) and transition metal chalcogenide (CdO, PbS) nanoparticles are studied using time-dependent density functional theory (TD-DFT) calculations on (MX)32 nanoparticles. We demonstrate, just as we previously showed for MgO, that TD-DFT calculations on rocksalt nanoparticles require the use of hybrid exchange–correlation (XC-)functionals with a high percentage of Hartree–Fock like exchange (e.g. BHLYP) or range-separated XC-functionals to circumvent problems related to the description of charge-transfer excitations. Concentrating on the results obtained with TD-BHLYP we show that the optical gap in rocksalt nanoparticles displays a wide range of behavior; ranging from large optical gaps stemming from a localized excitation involving corner atoms in alkaline earth oxides to a delocalized excitation and small optical gaps in the transition metal chalcogenides. Finally, we rationalize this wide range of behaviour in terms of differences in the degree to which the Coulombic interaction between the excited electron and hole is screened in the different nanoparticles, and relate it to the optical dielectric constants of the bulk materials the nanoparticles are made from.

Graphical abstract: Chemical trends in the optical properties of rocksalt nanoparticles

Supplementary files

Article information

Article type
14 Aug 2015
25 Sep 2015
First published
25 Sep 2015
This article is Open Access
Creative Commons BY license

Phys. Chem. Chem. Phys., 2015,17, 28892-28900

Author version available

Chemical trends in the optical properties of rocksalt nanoparticles

M. C. C. Wobbe and M. A. Zwijnenburg, Phys. Chem. Chem. Phys., 2015, 17, 28892 DOI: 10.1039/C5CP04851F

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