  The structures of odd-odd $N=Z$ nuclei in the lower \emph{fp} shell have been
investigated with a new isospin-nonconserving microscopical interaction. The
interaction is derived from a high-precision charge-dependent Bonn
nucleon-nucleon potential using the folded-diagram renormalization method.
Excellent agreements with experimental data have been obtained up to band
terminations. Particularly, the relative positions of T=0 and T=1 bands were
well reproduced. Calculations with another interaction obtained from the
Idaho-A chiral potential showed similar results. Our calculations also give a
good description of the existence of high-spin isomeric states in the
$0f_{7/2}$ sub-shell. As examples, the spectroscopies and isospin structures of
$^{46}$V and $^{50}$Mn have been discussed in detail, with the useful
predictions of level structures including electromagnetic properties. Results
for $^{50}$Mn were analyzed where experimental observations are still
insufficient.
