Liquid n-tridecane near impenetrable walls by Monte Carlo simulations

3 Liquid n-tridecane near impenetrable walls by Monte Carlo simulations 

The first calculation on atomistic systems of chain molecules near solid surfaces was performed in Ref. 21 modeling the surfaces as two impenetrable walls placed at a distance much greater than the molecular dimensions. The overall chain density of the model has been chosen such that the local density far from the walls was equal to that of the bulk liquid at 300 K. Since all the properties of molecules far from the walls were found to match those of unperturbed chains, as described by the rotational isomeric state (RIS) model at this temperature, the chains in contact with the impenetrable walls can be considered to be in equilibrium with the unperturbed bulk liquid. 

The reduced density of molecular centers of mass (cm), that is the density of centers of mass divided by the corresponding bulk value, shows a large maximum at z between 0.1 and 0.3 nm (Fig. 8.3). This distinct maximum shows that most of the chain segments adjacent to the walls belong to the practically flat two-dimensional chains. The distribution of units of chains 

5 The intermolecular orientational correlation parameter of two bond segments, s,j(d), in the first layer of 0.2 nm thiekness adjacent to the walls and in a similar layer far from the walls. (Redrawn from Ref. 21.) 

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