= Ginzburg reduced-temperature window
{c}
{title2=$\mathrm{Gi}\sim[u c^{-d/2}a_t^{(d-4)/2}]^{2/(4-d)}$}
For dimensionless scalar <Landau-Ginzburg theory> with quadratic coefficient $r=a_t t$, <gradient> coefficient $c>0$ and quartic term $u\phi^4/4$, the <correlation-volume derivation of the scalar Ginzburg ratio> gives $\mathcal G\sim u c^{-d/2}a_t^{(d-4)/2}|t|^{-(4-d)/2}$. For $d<4$, solving $\mathcal G\sim1$ gives the displayed nonuniversal window. Mean-field self-consistency requires $|t|\gg\mathrm{Gi}$ while still staying in the domain of the local expansion. In three dimensions $\mathrm{Gi}\sim u^2/(c^3a_t)$. Numerical prefactors depend on the averaging convention and microscopic normalization; no universal material value follows from dimensional power counting. At four dimensions use the <marginal Ginzburg criterion> instead of this singular exponent formula.
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