Rotational Isomeric State DRIS Model

Dynamic Rotational Isomeric State (DRIS) Model 

An extension of the original RIS theory deals with how the RIS theory may be extended to deal with dynamic processes in single chains. Rapid relaxation processes in polymers are related to local conformational transitions of 

The scheme just described assumes that the bond undergoes independent conformational transitions. The rate transition scheme becomes more complicated in the case of pairwise-dependent conformational transitions. In this case, one needs to solve 

The elements of P now give the probability that a given pair of bonds is in one set of states at time t and at another pair of states at time 0. 

The concept may be extended to include the motion of a sequence of N bonds. For the case of independent conformational transitions one obtains 

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The elements of the transition rate matrix A in the DRIS model are estimated from the multidimensional energy surface associated with the interdependent rotation of neighboring bonds u g Kramers rate theory, as described above. Accordingly, the probability of occurrence of a given isomeric state for a bond depends on the state of its first neighbors aloi the chain. Likewise, in the kinetic Ising model the transition rate Wi(Oi) of the i-th spin is assumed to be coupled to the state of its first iKighbors by the relation... 

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