Monte Carlo simulation of Lennard-Jones chains

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Abstract
Thermodynamical properties of ‘‘infinitely stiff’’ freely jointed Lennard‐Jones chains are obtained through Monte Carlo simulation technique in the canonical (NVT) ensemble. A force‐bias sampling scheme is used in the simulation. The compressibility factor, energy, and constant‐volume heat capacity of 8‐, 16‐, and 32‐mer Lennard‐Jones chains over wide ranges of densities and temperatures are obtained. It is known that the virial pressure of infinitely stiff freely jointed Lennard‐Jones chains depends on two‐ and three‐body correlations between segments. We determine, for the first time, these two contributions to the virial pressure of Lennard‐Jones chains, and found that their relative magnitudes are comparable with each other. While the three‐body term remains positive for all temperatures and densities examined, the two‐body term adopts negative values at low temperatures and densities and positive values at high temperatures and densities. Our simulation results reveal the importance of three‐body intrachain correlations that arise from chain connectivity and provide a quantitative basis for the assessment and development of theories for chain fluids.