Short-time dynamics behavior at the gas-liquid critical point

The dynamic relaxation process for the two dimension fluid at the critical point was studied, by using the constant pressure and constant temperature (NPT) molecular dynamics (MD). The system was initially at the state of ver y high temperature and of the density little higher than the critical densi ty, and then it was quenched to the state of the critical temperature and c ritical pressure. The initial increase of the density was observed. The new dynamic exponent theta has been obtained and it manifests the universal sh ort-time dynamic behavior also exists in the fluid phase. (C) 2000 Elsevier Science B.V. All rights reserved. PACS: 71.15.D; 64.60.F; 05.70.Jk.