Materials modelling on atomic scales
Over the past years, the phase-field approach has become the method of choice for modelling complex microstructures during phase transformations, namely changes in the pattern of atoms. It allows the description of microstructures and their evolution in both time and space under realistic conditions using conserved and non-conserved variables. The EU-funded project PHASEFIELD (Approximations to dynamic density functional theory - Phase field simulations on atomic scales) was devoted to increasing simulations' length and time scales for modelling self-assembly of quantum dots and molecular interactions in microfluidics devices. Several milestones were reached in this direction. Using the phase-field approach, the microstructure of a crystalline material is modelled by high-order partial differential equations. Generally, they cannot be solved analytically, but researchers have been developing tools to solve them numerically. The continuous equations were replaced with their discrete counterparts and the time step was adapted to obtain meaningful solutions. Furthermore, the PHASEFIELD team explored the approximations made to derive the phase-field model of crystals' microstructure using the atomic density functional theory. The purpose of linking the formalism of the classical theory with the newest extension of the phase-field modelling is to exploit their connection to develop multi-scale models. Although significant progress has been made, many challenges remain. Exactly how capable microstructure modelling is at revealing how the materials must be handled needs to be evaluated. This is a key element in materials quality control defining the final functionality of materials. For example, the crystal structure and impurity content of silicon determine its performance in electronics. To date, technological advancement has always been linked to the ability to synthesise new materials with complex organised microstructures and exploit their properties. Modelling at the atomic scale pursued within PHASEFIELD is expected to have a significant impact on the way materials are designed and manufactured in the near future.
Keywords
Atomic scales, microstructure, PHASEFIELD, density functional theory, crystalline material
