  We develop an efficient sampling method by simulating Langevin dynamics with
an artificial force rather than a natural force by using the gradient of the
potential energy. The standard technique for sampling following the
predetermined distribution such as the Gibbs-Boltzmann one is performed under
the detailed balance condition. In the present study, we propose a modified
Langevin dynamics violating the detailed balance condition on the
transition-probability formulation. We confirm that the numerical
implementation of the proposed method actually demonstrates two major
beneficial improvements: acceleration of the relaxation to the predetermined
distribution and reduction of the correlation time between two different
realizations in the steady state.
