Free energy calculation of extended defects through simulated alchemy: application to Ni3Al antiphase boundaries

Publisher Website
Google Scholar
Abstract
Accurate calculation of the free energy of defects is important in understanding many mechanical processes and properties in materials. Here a method is proposed for directly calculating the free energy difference between bulk crystal and defect multi-component atomic systems. Based on lambda -integration techniques it involves defining a nonphysical but reversible thermodynamic pathway that connects the bulk reference crystal and defect structures. This pathway can be thought of as an alchemic route to the free energy as selected atoms are allowed to transform their atomic character. The method is demonstrated by using it to calculate the free energy of Ni3Al antiphase boundaries where atomic interactions are modeled through a Finnis-Sinclair type potential.