  The effect of umklapp scattering on interchain hopping has been investigated
for two-coupled chains of interacting electrons with half-filled band. By
analyzing in terms of renormalization group method, we have found that
interchain hopping is renormalized to zero and is confined when a gap induced
by umklapp scattering becomes larger than a critical value. From a phase
diagram calculated on a plane of the interchain hopping and the gap, we discuss
a role of the correlation gap which has been studied in metallic state at
temperatures above spin density wave state in organic conductors.
