A Fokker–Planck equation is a deterministic equation for the time dependent probability density P ( A , t ) of stochastic variables A . The Fokker–Planck equation corresponding to the generic Langevin equation described in this article is the following: ∂ ∂ P ( A , t ) ∂ ∂ t = ∑ ∑ i , j ∂ ∂ ∂ ∂ A i ( − − k B T [ A i , A j ] ∂ ∂ H ∂ ∂ A j + λ λ i , j ∂ ∂ H ∂ ∂ A j + λ λ i , j ∂ ∂ ∂ ∂ A j ) P ( A , t ) . The equilibrium distribution P ( A ) = p 0 ( A ) = const × × exp ⁡ ⁡ ( − − H ) is a stationary solution.