  The five-loop effective potential and the associated summation of subleading
logarithms for O(4) globally-symmetric massless $\lambda\phi^4$ field theory in
the Coleman-Weinberg renormalization scheme $\frac{d^4V}{d\phi^4}|_{\phi = \mu}
= \lambda$ (where $\mu$ is the renormalization scale) is calculated via
renormalization-group methods. An important aspect of this analysis is
conversion of the known five-loop renormalization-group functions in the
minimal-subtraction (MS) scheme to the Coleman-Weinberg scheme.
