Calculation of Energy Gap on Alkaline Earth Mixed Halides and Correction of the Chemical Bond Ionicity

A semi-empirical formula for energy gap calculation is obtained from the Lorentz electron theory of solids. The calculated results of energy gap on alkaline earth mixed halides are reasonable. The classical bond ionicity is corrected from the consideration of both the electronegativity difference and bond distance. It is revealed that the corrected ionicity is more suitable to characterize the chenmical bonds.