Nearest-neighbor distance reversible

The method based on the orientation of pairs of vectors of length L produces slower dynamics than the method based on next-nearest neighbor distances. Since the acceptance rates for single-bead moves differ very little in the two methods, it appears that the probability for immediate reversal of a successful move is higher in the method based on the orientation of the pairs of vectors, such that the chain shivers rapidly, but moves its center of mass slowly. This problem is more severe in PP melts than in PE melts. Significant diffusion of the center of mass of the chains in PP melts is achieved when reptation, as well as single-bead moves, is allowed [158, 158A]. 

In weak or reversible gels the bonds may form and break in thermal equilibrium ( annealed bonds ). The probability p for two monomers at nearest-neighbor distance to form a bond depends on the other two variables temperature and concentration (or even on other variables if they exist) ... 

The charge distribution determined within clusters by CNDO has been reported for only a few cases. Let us consider only one cluster, the 13-atom fee cluster with only two geometrically different types of atom. There is a center atom with 12 nearest neighbors, and there are 12 surface atoms each with 4 nearest neighbors. At the equilibrium bond length (0.34 nm) the center atom has a net positive charge, but this situation is reversed at the bulk experimental distance (0.288 nm). 

In each case the bridging distance in the trifluorides of Nb. Mo, Ru, and Rh are quoted to be shorter than that for the corresponding distance in the pentafluoride. This difference is significant in the case of Rh, is nearly so for Ru, and appears likely to be real for the others also. Because the trifluoride of an element has two more ir electrons than a pentafluoride, M-Fb in the former ought to be weaker, and the interatomicdistances longer, than in the latter. The reverse situation is observed. It appears, therefore, that the impact of F—F nearest-neighbor... 

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