We present a quantitative two-band theory which describes analytically the
composition dependence of the energy gap, interband momentum matrix element
and band edge effective masses in GaNxAs1-x alloys for x < similar to 0.1.
The model is confirmed using an sp(3)s* tight-binding Hamiltonian, whose r
esults agree well, both with experiment and previous pseudopotential calcul
ations. (C) 1999 Elsevier Science Ltd. All rights reserved.