Pressure dependence of the band gaps in Si quantum wires

The pressure coefficients a of interband transitions in (001) silicon wires are calculated using a plane-wave basis and carefully fitted empirical pseudopotentials. We find purely red shifts (a<0). Their magnitudes, as well as changes with wire sizes can be interpreted in terms of the ‘‘truncated crystal model’’ which describes the wire conduction bands as linear combination of the lowest bulk conduction bands along the Γ-X line.