  Pinning phenomena in an incommensurate two-chain model of friction are
studied numerically. The pinning effect due to the breaking of analyticity
exists in the present model. The pinning behavior is, however, quite different
from that for the breaking of analyticity state of the Frenkel-Kontorova model.
When the elasticity of chains or the strength of interchain interaction is
changed, pinning force and maximum static frictional force show anomalously
complicated behavior accompanied by a successive phase transition and they
vanish completely under certain conditions.
