1,2 1 1 1 2 E g E g E g g 1/n 0 1 2 3 4 5 6 0 0.2 0.4 0.6 0.8 1 E g (eV) 1/n Symmetric 9 Symmetric 10 Symmetric 10 Symmetric 2 Asymmetric 11 Asymmetric 11 Symmetric 12 Symmetric 13 Asymmetric 14 Symmetric 6 1/n k