  We study electric transport near the Mott metal-insulator transition in a
triangular-lattice Hubbard model at half filling. We calculate optical
conductivity $\sigma(\omega)$ based on a cellular dynamical mean field theory
including vertex corrections inside the cluster. Near the Mott critical end
point, a Drude analysis in the metallic region suggests that the change in the
Drude weight is important rather than that in the transport scattering rate for
the Mott transition. In the insulating region, there emerges an "ingap" peak in
$\sigma(\omega)$ at low $\omega$ near the Mott transition, and this smoothly
connects to the Drude peak in the metallic region with decreasing Coulomb
repulsion. We find that the weight of these peaks exhibits a power-law behavior
upon controlling Coulomb repulsion at the critical temperature. The obtained
critical exponent suggests that conductivity does not correspond to
magnetization or energy density of the Ising universality class in contrast to
several previous works.
