Atomistic Simulations in bcc Metals

Abstract

It is clear that numerical methods essential when trying to understand the detailed atomic structure and dynamics. The most popular quantum mechanical approach is density functional theory (Martin, Electronic structure: basic theory and practical methods, 2004, [1]) (DFT), which exploits an isomorphism between the ground state wave function and ground state electron density to approach the many-body Schrödinger equation variationally, often allowing efficient evaluation of complex structures and energy landscapes. However, even with significant simplifications to the underlying Hamiltonian such techniques are currently limited to less than 500 metallic atoms, meaning that they only be used to inform coarse grained models of atomic interaction. At present, short segments of screw dislocation cores can be simulated in DFT allowing accurate parametrisation of the Peierls barrier and dislocation formation energies, along with similar properties for point defect formation energies, as well as bulk properties such as the lattice parameter and bulk modulus (Marinica et al., J Phys Condens Matter 25(39):395502, 2013, [2]). It is the aim of any coarse grained model to quantitatively reproduce these features as accurately as possible.