A computational study of elastic properties of disordered systems with voids

We present a computational study of elastic properties of disordered systems with voids. The influence of hydrogen and voids on the elastic properties has been investigated by means of atomistic simulations using empirical potentials for hydrogenated amorphous silicon. The elastic constants have been obtained from the fluctuations of the simulation cell in Monte Carlo simulations at constant pressure and temperature. Our results indicate that the softening of the elastic constants of a-Si:H observed experimentally upon increasing hydrogen content cannot be explained by a weakening of the network induced by the reduced coordination but should be attributed instead to the formation of voids. A simple relation between Young’s modulus and the density is presented.