Influence of quench rate and pressure on the glass transition temperature in selenium

We report a molecular dynamics investigation of the glass transition temperature in selenium at pressures ranging from 0 to 6 GPa as a function of the quench rate, Q(r). For moderate pressures the specific volume of the glass depends strongly on the quench rate, whereas the specific enthalpy varies only little. We find for both volume and energy a linear dependence on the quench-rate-dependent glass transition temperature. The slopes of these curves reflect the different energy scales of void formation, inter- and intrachain interactions. The extrapolated glass transition temperatures for quench rates of order K/s agree with the experimental ones within 20%. Applying a pressure of 1 GPa the glass transition temperature is raised by 37 K. For the same Q(r), the transition temperature T-g is much higher for simulations using fixed volume conditions (NVT ensemble) than for the ones using fixed pressure (NPT ensemble) when one compares results for equal pressure at T=0. (C) 2002 American Institute of Physics