Molecular chain length cutoffs

There have been many analytic and numerical studies of the structure that solids induce in an adjacent fluid. Early studies focussed on layering in planes parallel to a flat solid surface. The sharp cutoff in fluid density at the wall induces density modulations with a period set by oscillations in the pair correlation function for the bulk fluid [169 173]. An initial fluid layer forms at the preferred wall fluid spacing. Additional fluid molecules tend to lie in a second layer, at the preferred fluid fluid spacing. This layer induces a third, and so on. The pair correlation function usually decays over a few molecular diameters, except near a critical point or in other special cases. Simulations of simple spherical fluids show on the order of 5 clear layers [174 176], while the number is typically reduced to 3 or less for chain or branched molecules that have several competing length scales [177 180]. 

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