1.50 2.50 1.25 2.25 /B 1.00 2.00 P Of 0.75 1.75 1.50 0.50 1.25 0.25 E (eV) relative from top of VB 1.00 0.00 0.75 -0.25 0.50 0.25 1 -0.50 0.00 -0.75 -0.25 -1.00 -0.50 -6.0x109-4.0x109-2.0x109 0.0 2.0x109 4.0x109 6.0x109 -2x109 -1x109 0 1x109 k (1/m) along x-direction k (1/m) along x-direction