Irreducible Brillouin Zone for 2D Phononic Crystals with Different Configurations
Plane-wave expansion method are employed to investigate the effect of point-group symmetry to the irreducible Brillouin zone(BZ) of two-dimensional phononic crystals(PCs). Based on the calculations of four kind configurations with different symmetry, we find that the irreducible BZ will enlarge with the lower of the point-group symmetry of PCs and some of the maximums or minimums of bands are not locate at the periphery of the irreducible BZ. Therefore, the previous calculations of band structure, considering only the periphery of the irreducible BZ, is incomplete for PCs with low point-group symmetry. We analyze this problem and give a guide for further investigations in the paper, which is important to obtain accurate band structure of PCs with low point-group symmetry.