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arXiv · 0801.0381

Electron Emission from Diamondoids: A Diffusion Quantum Monte Carlo Study

N. D. Drummond·A. J. Williamson·R. J. Needs·G. Galli
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Abstract

We present density-functional theory (DFT) and quantum Monte Carlo (QMC) calculations designed to resolve experimental and theoretical controversies over the optical properties of H-terminated C nanoparticles (diamondoids). The QMC results follow the trends of well-converged plane-wave DFT calculations for the size dependence of the optical gap, but they predict gaps that are 1-2 eV higher. They confirm that quantum confinement effects disappear in diamondoids larger than 1 nm, which have gaps below that of bulk diamond. Our QMC calculations predict a small exciton binding energy and a negative electron affinity (NEA) for diamondoids up to 1 nm, resulting from the delocalized nature of the lowest unoccupied molecular orbital. The NEA suggests a range of possible applications of diamondoids as low-voltage electron emitters.

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N. D. Drummond, A. J. Williamson, R. J. Needs, G. Galli. 2008-01-02. Electron Emission from Diamondoids: A Diffusion Quantum Monte Carlo Study. https://doi.org/10.1103/physrevlett.95.096801

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