The name is absent

Thus, the evaluation of the free energies and their derivatives require computing a
functional integral given by eqn. 8.37 while the observable properties like the fluid
structure require computing two functional integrals. In practice, for non-trivial mod-
els of three-dimensional fluids, none of these functional integrals can be evaluated in
closed form. Hence, analytical approximations have been developed.

SCFT employs the most successful approximation technique known as the mean
field approximation. Mean field approximation assumes that a single field configura-
tion w*(r) dominates the field integrals in eqs. 8.37 and 8.38. This field configuration
known as the mean-field or self-consistent field, is obtained by demanding that 7∕[w]
be stationary w.r.t. variations in w(r), or

Thus,

Z ≈ exp (—77[w*]),

and

(φ])≈GH

Thus, the mean field approximation neglects all “field fluctuations”. Apparently, this
is a good approximation for concentrated solution or melts of high molecular wight
polymers [250]. Since the effective co-ordination number of the segments in polymer
melts grows as the square root of the molecular weight, the field fluctuations are

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