Dirac Points in Two-Dimensional Inverse Opals

The electron energy states and energy bands are calculated for a two-dimensional inverse opal structure. Assume that the opal structure is closed-packed circles, the inverse opal has the honeycomb lattice. The honeycomb lattice in two dimensions has a Diract point. Its properties can be manipulated by altering the structure of the inverse opal: the radius of the circle, and the small gap between circles.