Pressure control in tight-binding molecular dynamics: Application to a-Si formation

We introduce a mechanism far pressure control into an otherwise conventional tight-binding molecular-dynamics algorithm A generalized enthalpy is derived, which is conserved in our dynamics, and which can hence be used to assess the accuracy of the implementation. We use this algorithm to study the influence of the pressure during a-Si preparation by quenching from the melt. A deeper potential energy minimum is reached when a-Si is prepared at zero pressure. Furthermore, modifications in the short-and intermediate-range order show up. This demonstrates that pressure control in the preparation of a-Si is advisable.