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

作者：Tiwald Paul^*; Karsai Ferenc; Laskowski Robert; Graefe Stefanie; Blaha Peter; Burgdoerfer Joachim; Wirtz Ludger

来源：Physical Review B, 2015, 92(14): 144107.

DOI：10.1103/PhysRevB.92.144107

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 (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 approximate to 1.8.

• 出版日期2015-10-14