Numerical study of the defect adamantine compound CuGaGeSe4

ABSTRACTThe electronic structure, elastic and optical properties of the defect adamantine compound CuGaGeSe4 in structure are systematically investigated using first-principles calculations. Through detailed calculation and comparison, we obtain three independent atomic arrangements and predict the most stable atomic arrangement according to the lattice constants and enthalpy formation energies. The elastic constants are calculated, which can be used to predict the axial thermal expansion coefficients accurately. The optical properties of compound CuGaGeSe4, including the dielectric function, refractive index and absorption spectrum, are depicted for a more intuitive understanding. Our calculated zero-frequency limits ϵ1(0) and n(0) are very close to the other theoretical values, which proves that our calculations are reliable.