First-Principles Calculations Of Structural, Electronic And Elastic Properties Of Tysonite Lanthanum Fluoride (Laf3)

Abstract

The structural, electronic and elastic properties of tysonite Lanthanum fluoride (LaF3) have been studied using Density Functional Theory. The lattice constants were calculated and then the values fitted into the energy volume relation using the Birch-Murnaghan third order equation of state. Lattice parameter in this calculations are as follows; a = 7.245Å, c = 7.388Å and c/a = 1.02Å against 7.128Å, 7.329Å and 1.028Å of CASTEP. A band gap of 7.78eV was obtained in comparison to the 9.0eV of experiment and this is because DFT-GGA/LDA is known to underestimate band gaps. The results for elastic constants for the directions C11 = 170.1, C12 = 76.26, C13 = 58.69, C14 = -1.66, C33 = 208.08 and C44 = 33.90. Compared to other theoretical and experimental values, these results are in good agreement.