Pretransitional chain stretching

We emphasize at this point that all these pretransitional chain stretching effects found in the simulations are at variance with the simple RPA treatment as embodied in Leibler s theory this simple form of the RPA would mean only that all the ratios shown in Fig. 7.38 should be strictly unity, irrespective of e and N. Thus the simulations reveal rather drastic deviations from RPA, a hitherto somewhat unexpected result, since for dense melts the RPA has been taken as basically exact by many researchers. In this context, it is also important to recall that these deviations from the RPA should not be attributed to the vacancy content of the model (recall that Fig. 7.17(a) has studied this behavior for variable vacancy content, and behavior independent of cj>v for T > Tc was found " ). 

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