Electronic Structure and Ground State Properties of A4[Cu4O4] (A=Li, Na, K and Rb): A First Principle Study

The results of first principles calculations of the electronic band structure and ground-state properties of alkali metal copper oxides A4[Cu4O4] (A = Li, Na, K and Rb) compounds are in tetragonal body centered structure with two different space groups I-4m2 and I4/mmm. The calculations have been carried out using the tight-binding linear muffin-tin orbital method within the local density approximation. The total energies calculated within the atomic sphere approximation where used to determine the ground-state properties such as equilibrium lattice parameters, c/a ratio, the bulk modulus and cohesive energy and these are found to be in good agreement with the available experimental values. The results of the electronic band structure calculations show that LiCuO, KCuO and RbCuO are indirect band gap semiconductors, whereas NaCuO is direct band gap semiconductor.