Let A = { A i } denote the slow variables. The generic Langevin equation then reads d A i d t = k B T ∑ ∑ j [ A i , A j ] d H d A j − − ∑ ∑ j λ λ i , j ( A ) d H d A j + ∑ ∑ j d λ λ i , j ( A ) d A j + η η i ( t ) .