  In complex systems such as spin systems and protein systems, conventional
simulations in the canonical ensemble will get trapped in states of energy
local minima. We employ the generalized-ensemble algorithms in order to
overcome this multiple-minima problem. Two well-known generalized-ensemble
algorithms, namely, multicanonical algorithm and replica-exchange method, are
described. We then present four new generalized-ensemble algorithms as further
extensions of the two methods. Effectiveness of the new methods are illustrated
with a Potts model, Lennard-Jones fluid system, and protein system.
