modified Benedict–Webb–Rubin — Lennard-Jones 12/6 chain

This noncubic EOS describes the behaviour of the Lennard-Jones 12/6 fluid as well as flexible LJ tangent-sphere chains.

The EOS consists of a BWR EOS for single LJ spheres and an extension term for chain molecules. The LJ EOS has been fitted to computer simulation data. It is similar to the older Nicolas EOS [1] (= mBWR1-LJ), but based on a more extensive and accurate set of simulation data [2]. The chain term is based on the behaviour of the background correlation function (cavity correlation function) at contact and uses a superposition approach to relate this function for chain molecules to that of spherical particles [3].

Users interested in the accurate representation of the LJ 12/6 EOS should also consider the EOSs of Kolafa and Nezbeda, Quiñones-Cisneros or Mecke et al.. For 2-center LJ molecules, the EOS of Lísal et al. can be recommended.

The critical compression factor of this EOSs is somewhat too high (0.319 for 1-center LJ molecules) and increases with chain length, in contrast to the behaviour of real molecules.

adjustable parameters: 3
The ThermoC parameters are T* = ε/kB, v* = NAσ3, and m (number of sites).

[1] J. J. Nicolas, K. E. Gubbins, W. B. Streett, and D. J. Tildesley, Mol. Phys. 37 (1979) 1429–1454.

[2] J. K. Johnson, J. A. Zollweg, K. E. Gubbins, Mol. Phys. 78 (1993) 591–618.

[3] J. K. Johnson, E. A. Müller, K. E. Gubbins, J. Phys. Chem. 98 (1994) 6413–6419.

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