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We use ab initio total-energy minimization techniques to resolve the lattice strain βh arising from the presence of holes in the valence band of SiGa alloys. We find, in agreement with recent EXAFS results, the lattice to contract upon increasing the proportion of holes (βh < 0). We also find that the valence-band deformation potential av is positive, leading to a violation of Keyes' relation, which asserts that βh and av are equal within a constant positive factor. Our calculations suggest therefore that Keyes' formula does not describe adequately the relation between the two quantities, and also resolve the apparent contradiction between experiment and previous calculations.

We present an approximate scheme for the dynamical annealing of electrons in Car-Parrinello-type calculations. Our approach is based on the use of the total electron density (rather than the wave functions) as the fictitious variable that drives the annealing. The Thomas-Fermi approximation is employed to describe the kinetic energy of the electrons. Our calculation of the ground-state configuration of either c-Si or H/Si(100)1 × 1 is found to be in excellent agreement with both experiment and detailed Car-Parrinello simulations. The method can be used as an “economical” first-order solution to numerous structure-optimization problems.

The Monte-Carlo simulation method has been used to simulate the growth of the f.c.c. (111) crystal surface, on which emerged the outcrop of a stacking fault bounded by two partial dislocations. The comparison of the growth rates has been made between the stacking-fault-containing surface and the perfect surface. The successive growth stages have been simulated. The influence of the width of the stacking fault on the growth rates of the (111) surface has also been studied. We conclude that the outcrop of the stacking fault bounded by two partial dislocations on the crystal surface can act as a self-perpetuating step-generating source.

Effects of many-body interactions on crystal-vapor interface are studied by employing Monte Carlo method with an anisotropic variable bond model. We conclude that, because of surface relaxation, the surface free energy and the edge free energy decrease, crystal growth rate increases, and the surface roughening transition temperature is lowered.

Monte-Carlo simulation technique with an anisotropic variable bond model is used to simulate the vapor growth on (100), (111) and (110) faces of a f.c.c. crystal. The effects of many-body interactions on crystal growth kinetics, crystal morphology and kinetic roughening are discussed.

Monte Carlo simulation technique with an anisotropic variable bond model is used to simulate the vapor growth of a simple Kossel crystal. We conclude that an anisotropic variable bond approach would predict a lower roughening transition temperature than those obtained by a conventional constant bond approach and the isotropic variable bond approach proposed by Ong et al.