Tight-binding molecular-dynamics study of a-Si:H:: Preparation, structure, and dynamics

We describe a-Si:H using a tight-binding Hamiltonian which is based on s, p, and d orbitals for Si and s orbitals for H. The sample is prepared by quenching a Si (6.25%) H mixture from the gas phase at zero pressure. The condensation phase transition is clearly observed at roughly 2500 K. The resulting a-Si:H specimen has a density of 2.35 g/cm(3); Si atoms are mainly fourfold coordinated, with around 7% fivefold coordinated atoms, while H atoms exhibit a tendency for clustering. As a specific example for a dynamic event, we study the structural rearrangements occurring after breaking a Si-H bond. [S0163-1829(99)05531-9].