The Rouse model has recently been modified to take into account the excludedvolume interactions that exist between various parts of a polymer chain byincorporating a narrow Gaussian repulsive potential between pairs of beads onthe Rouse chain (cond-mat/0002448). The narrow Gaussian potential ischaracterized by two parameters: z* - which accounts for the strength of theinteraction, and d* - which accounts for the extent of the interaction. In thelimit of d* going to zero, the narrow Gaussian potential tends to the morecommonly used delta-function repulsive potential. The influence of theparameter d*, in the limit of infinite chain length, on equilibrium and linearviscoelastic properties, and on universal ratios involving these properties, isexamined here. A renormalization group calculation of the end-to-end vectorsuggests that the value chosen for the variable d* will not affect criticalexponents, or universal ratios. A similar trend is also observed for resultsobtained with an approximate solution, which is based on the assumption thatthe non-equilibrium configurational distribution function is Gaussian.
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