NONEQUILIBRIUM MOLECULAR-DYNAMICS - THE 1ST 25 YEARS

Equilibrium molecular dynamics has been generalized to simulate nonequilibrium systems by adding sources of thermodynamic heat and work. This generalization incorporates microscopic mechanical definitions of macroscopic thermodynamic and hydrodynamic variables, such as temperature and stress, and augments atomistic forces with special boundary, constraint and driving forces capable of doing work on, and exchanging heat with, an otherwise Newtonian system: p = F(A)(q) + F(B)(q) + F(C)(q,p) + F(D)(q,p) = m(q(t+dt) - 2q(t) + q(t-dt))/dt2. The underlying Lyapunov instability of these nonequilibrium equations of motion links microscopic time-reversible deterministic trajectories to macroscopic time-irreversible hydrodynamic behavior as described by the second law of thermodynamics. Green-Kubo linear-response theory has been checked. Nonlinear plastic deformation, intense heat conduction, shock-wave propagation, and nonequilibrium phase transformation have all been simulated. The nonequilibrium techniques, coupled with qualitative improvements in parallel computer hardware, are enabling simulations to approximate real-world microscale and nanoscale experiments.