Mass transport in solids, where different chemical species diffuse in a material due to random motion with or without a driving force, is a fundamental kinetic process for a wide variety of materials problems. Professor Trinkle will present an alternative derivation of the transport coefficients, and show that it can be recast as a variational problem, where the true transport coefficients are minimal against variations in state position. These new developments will lead to significant new modeling capabilities with unprecedented accuracy and computational efficiency to computationally predict mass transport, capable of impacting the development of advanced alloys, battery materials, control of corrosion, and new processing methods.