  We discuss the optimized switching free energy simulations in an analogy with
the systems which are driven under nonequilibrium feedback control. We find an
on-the-fly simulation approach of switching optimization is a special case of
the nonequilibrium process under feedback control. In this approach, the
switching rate is allowed to vary during the simulation and the optimization is
done on-the-fly by utilizing the part of the simulation outcomes as the
feedback information. In such a case, one should use generalized Jarzynski
equality under nonequlilibrium feedback control for free energy calculation
instead original Jarzynski equality.
