  Appropriate candidates of the metallic sheet used for the electrodes of
diamond semiconductor are investigated using computational approaches based on
density functional theory (DFT). For twenty kinds of metallic elements $x$, we
modeled a diamond-metal interface and evaluated its work of separation,
$W_\mathrm{sep}(x)$, as a possible measure of anti-peeling strength. The
appropriateness of the Ohmic contact was inferred from DOS (density of states)
analysis of diamond-metal interface by looking at whether an in-gap
(isolated/localized) peak disappears as well as a sufficient amount of DOS
value exists around the Fermi level. Our DFT simulation confirmed that a
typical electrode, Au, is not adhesive enough for power devices
[$W_\mathrm{sep}(\mathrm{Au}) = 0.80$ J/m$^2$], though showing the Ohmic
contact. In contrast, some transition metals were found to possess Ohmic
features with much stronger adhesion than Au [e.g.,
$W_\mathrm{sep}(\mathrm{Cr}/\mathrm{Ti}) = 6.02/4.03$ J/m$^2$].
