 The density of states in an energy interval formula_8 depends on the number of states in an interval formula_7 in reciprocal space and the slope of the dispersion relation formula_3.Though the lattice cells are not spherically symmetric, the dispersion relation still has spherical symmetry from the point of view of a fixed central point in a reciprocal lattice cell if the dispersion relation is extended outside the central Brillouin zone.The density of states in a three-dimensional lattice will be the same as in the case of the absence of a lattice.