FIG. 2 (color online). Calculated band structure for commensurate monolayer of Bi on Cu(111). States marked in red (or gray) and blue (or dark gray) are Bi-derived unoccupied and occupied QW states, Cu states are shown in black. The size of the symbol is a measure of the weight of the states in the vacuum. For better visibility, the weight of the occupied states (blue) is multiplied by a factor 5. Cuts through the charge densities of three Bi states from the point are shown: at the left, the (occupied) state at E EF ¼ 1:0 eV and, at the right, two unoccupied states at E EF ¼ 2:1 and 2.7 eV. With increasing energy the weight of the states in the vacuum can be seen to increase. The cuts show the upper eight Cu layers and go through the two Bi atoms in the unit cell. In the band structure, the Cu surface state from the other side of the film is visible as black circles.
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