Abstract: The tightbinding approximation is an important method for calculating electron energy bands in solids. Recently, an article incorrectly applied the tightbinding approximation to calculate the energy bands of hexagonal closepacked (hcp) lattice, resulting in complex energy eigenvalues. This paper identifies the doctrinal errors in their calculations, presents the correct calculation methods and results, and provides a detailed discussion on the symmetry of the energy bands, the extremal points, the characteristics of Bloch functions along highsymmetry paths, and the effects of nextnearest neighbor overlap integrals.

Key words: solid energy bands, tightbinding approximation, hexagonal closepacked lattice