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arXiv · 1507.02209

Ab-initio perspective on the Mollwo-Ivey relation for F-centers in alkali halides

P. Tiwald·F. Karsai·R. Laskowski·S. Gräfe·P. Blaha·J. Burgdörfer·L. Wirtz
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Abstract

We revisit the well-known Mollwo-Ivey relation that describes the "universal" dependence of the absorption energies of F-type color centers on the lattice constant $a$ of the alkali-halide crystals, $E_{\mbox{abs}}\propto a^{-n}.$ We perform both state-of-the-art ab-initio Quantum Chemistry and post-DFT calculations of F-center absorption spectra. By "tuning" independently the lattice constant and the atomic species we show that the scaling of the lattice constant alone (keeping the elements fixed) would yield $n=2$ in agreement with the "particle-in-the-box" model. Keeping the lattice constant fixed and changing the atomic species enables us to quantify the ion-size effects which are shown to be responsible for the exponent $n \approx 1.8$.

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P. Tiwald, F. Karsai, R. Laskowski, S. Gräfe, P. Blaha, J. Burgdörfer, L. Wirtz. 2015-07-08. Ab-initio perspective on the Mollwo-Ivey relation for F-centers in alkali halides. https://doi.org/10.1103/physrevb.92.144107

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