This implies the Onsager reciprocity relation λ λ i , j = λ λ j , i for the damping coefficients λ λ . The dependence d λ λ i , j / d A j of λ λ on A is negligible in most cases. The symbol H = − − ln ⁡ ⁡ ( p 0 ) denotes the Hamiltonian of the system, where p 0 ( A ) is the equilibrium probability distribution of the variables A . Finally, [ A i , A j ] is the projection of the Poisson bracket of the slow variables A i and A j onto the space of slow variables.