| 초록 |
In order to study the thermodynamic properties of chain and polymeric fluids in molecular level, we perform constant temperature molecular dynamics simulations of ’repulsive’ and ’full’ Lennard-Jones (LJ) chain fluids of lengths up to 16. In simulation, RATTLE algorithm to determine constraint forces and the Nose-Hoover thermostat to sample the canonical ensemble are used. For the repulsive LJ chains, the compressibility factor of the chain fluids is predicted from the first-order thermodynamic perturbation theory combined with the Week-Chandler-Andersen (TPT1-WCA) perturbation theory, and is compared to the simulation results. A good agreement between the theory and the simulation results is found particularly at liquid-like densities. For the full LJ chains, two different versions of TPT1 are used to calculate the compressibility factor : one is TPT1-WCA, and the other is TPT1 with the Percus-Yevick approximation for the radial distribution function of the LJ spheres (TPT1-PY). At low and intermediate densities, TPT1-PY gives better predictions for the compressibility of the LJ chain fluids whereas at high densities TPT1-WCA is more reliable.
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