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See detailAb initio perspective on the Mollwo-Ivey relation for F centers in alkali halides
Tiwald, Paul; Karsai, Ferenc; Laskowski, Robert et al

in Physical Review. B: Condensed Matter and Materials Physics (2015), 92

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 alkali-halide crystals, E-abs ... [more ▼]

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 alkali-halide crystals, E-abs proportional to 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 with the lattice constant alone 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 approximate to 1.8. [less ▲]

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See detailF center in lithium fluoride revisited: Comparison of solid-state physics and quantum-chemistry approaches
Karsai, Ferenc; Tiwald, Paul; Laskowski, Robert et al

in Physical Review. B : Condensed Matter (2014), 89

We revisit the theoretical description of the F color center in lithium fluoride employing advanced complementary ab initio techniques.We compare the results from periodic supercell calculations involving ... [more ▼]

We revisit the theoretical description of the F color center in lithium fluoride employing advanced complementary ab initio techniques.We compare the results from periodic supercell calculations involving density-functional theory (DFT) and post-DFT techniques with those from the embedded-cluster approach involving quantumchemical many-electron wave-function techniques. These alternative approaches yield results in good agreement with each other and with the experimental data provided that correlation effects are properly taken into account. [less ▲]

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See detailTowards an ab initio description of the charge transfer between a proton and a lithium fluoride surface: A quantum chemistry approach
Tiwald, Paul; Gräfe, Stefanie; Burgdörfer, Joachim et al

in Nuclear Instruments and Methods in Physics Research B (2013), 317, Part A

We study the non-adiabatic charge transfer dynamics during the collision of a slow proton with a lithium fluoride surface employing a quantum-chemistry based dynamics approach. The surface is modeled by ... [more ▼]

We study the non-adiabatic charge transfer dynamics during the collision of a slow proton with a lithium fluoride surface employing a quantum-chemistry based dynamics approach. The surface is modeled by an Li5F1+ H+ cluster embedded in a large matrix of point charges. Going beyond the adiabatic (or Born–Oppenheimer) approximation, we apply multi-reference configuration-interaction methods that allow for the calculation of ground and excited states of the embedded cluster as well as of the non-adiabatic couplings between them. This information serves as input for the determination of the neutralization probability of a proton scattered off a LiF surface using Tully’s semi-classical surface hopping algorithm. [less ▲]

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