Conformations Are Perturbed Near Surfaces

There are various ways to model the distributions of chain conformations near surfaces. Here we describe an approach based on a reflectance principle. It resembles the image charge approach in the theory of electrostatic interactions (see Chapter 21, page 399). 

The DiMarzio-McCrackin Reflectance Principle Predicts Chain Distributions Near Surfaces 

If there were no surface at all, the distribution of all conformations of a random-flight chain would be given by the Gaussian function, Equation (32.15), 

But the impenetrable plane eliminates some of these conformations. We want to count only the conformations that do not pass through the plane. The total number of conformations is the sum of viable conformations (those that don t cross the plane) and nonviable conformations (those that cross the plane)  

Equation (33.7) says that you can get the quantity you want, tr uabic. if you know tt nonviabie. because you have lytotai from Equation (33.6). 

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