A CPA calculation of E1 optical gaps in III-V ternary alloys

The E1 critical-point energies are calculated for the ternary alloys Gax- In1-xP, GaxIn1-xAs, GaAs1-xPx and InAs1-xPx in coherent-potential approximation using tight-binding Hamiltonian and neglecting spin-orbit effects. Good agreement, to within a few percent, is obtained between the calculated values of the E1 energy gap and the corresponding experimental values, for all the ternary systems studied here.