  The nonlinear conductance observed in a quantum point contact is
theoretically reproduced for the entire range of applied bias. The
single-impurity Anderson model with two reservoirs at different chemical
potentials is studied for a sequential change of the gate voltage. The
imbalance in the left and right Kondo coupling strength is introduced by the
displacement of the Kondo impurity by the electric field produced in the
constriction of quantum point contact. We reveal the origin of the side peaks
and study the behavior of the height and width of the zero-bias anomaly.
