We consider ternary and quaternary III‐V alloys whose constituent binaries are not lattice matched. The change in energy associated with the development of a composition modulation in these alloys is calculated in a single stage, without splitting it artificially between hypothetical ‘‘chemical’’ and ‘‘elastic’’ parts, as done up to now. The calculation, which consists of a numerical minimization of the microscopic elastic energy of the valence force field model, is illustrated for InxGa1−xAs. For most modulations along low index axes, the total energy is found close to the energy calculated by the two‐stage procedure. This confirms the stabilization by strain of the bulk III‐V alloys, justifies the use of a strain‐independent ‘‘chemical’’ energy in the description of inhomogeneous alloys, and strengthens our earlier demonstration of the reduced stability of the thin epitaxial layers of these alloys.
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