JOURNAL OF PHYSICS-CONDENSED MATTER, vol.18, no.20, pp.4887-4894, 2006 (SCI-Expanded)
We study the behaviour of GaAs under a uniaxial compression using an ab initio constant-pressure technique and find that GaAs undergoes a first-order phase transition to a side-disordered orthorhombic Imm2 structure via an intermediate state having the space group of I (4) over bar m2. The transition pathway and mechanism under uniaxial stress are found to be considerably different from those under the hydrostatic compression.