Transport diffusion of argon in AIPO4-5 from equilibrium molecular dynamics simulations

Transport diffusion of argon in the unidirectional channels of the molecular sieve AlPO4-5 has been studied using molecular dynamics simulations. Using the Green–Kubo formalism, this nonequilibrium property is, for the first time, extracted from just one equilibrium simulation. Apart from the computational advantages above nonequilibrium simulations, the new method also provides a way to check the validity of the assumption of linear response, which is at the basis of both methods. The transport diffusion coefficient for argon at 87 K and half the maximum loading is found to be equal to Dt = (1.4±0.1)×10–5 cm2/s, of which approximately 20% can be attributed to correlated, collective motion.