Strict detailed balance is unnecessary in Monte Carlo simulation

Detailed balance is an overly strict condition to ensure a valid Monte Carl o simulation. We show that, under fairly general assumptions, a Monte Carlo simulation need satisfy only the weaker balance condition. Not only does o ur proof show that sequential updating schemes are correct, but also it est ablishes the correctness of a whole class of new methods that simply leave the Boltzmann distribution invariant. (C) 1999 American Institute of Physic s. [S0021-9606(99)52606-8].