A multi-state modified embedded atom method potential for titanium
The continuing search for broadly applicable, predictive, and unique potential functions led to the invention of the multi-state modified embedded atom method (MS-MEAM) (Baskes et al 2007 Phys. Rev. B 75 094113). MS-MEAM replaced almost all of the prior arbitrary choices of the MEAM electron densities, embedding energy, pair potential, and angular screening functions by using first-principles computations of energy/volume relationships for multiple reference crystal structures and transformation paths connecting those reference structures. This strategy reasonably captured diverse interactions between atoms with variable coordinations in a face-centered-cubic (fcc)-stable copper system. However, a straightforward application of the original MS-MEAM framework to model technologically useful hexagonal-close-packed (hcp) metals proved elusive. This work describes the development of an hcp-stable/fcc-metastable MS-MEAM to model titanium by introducing a new angular function within the background electron density description. This critical insight enables the titanium MS-MEAM potential to reproduce first principles computations of reference structures and transformation paths extremely well. Importantly, it predicts lattice and elastic constants, defect energetics, and dynamics of non-ideal hcp and liquid titanium in good agreement with first principles computations and corresponding experiments, and often better than the three well-known literature models used as a benchmark. The titanium MS-MEAM has been made available in the Knowledgebase of Interatomic Models (https://openkim.org/) (Tadmor et al 2011 JOM 63 17).
|Keywords||density functional theory (DFT), embedded atom method (EAM), hexagonal closed-packed (hcp), modified embedded atom method (MEAM), multi-state modified embedded atom method (MSMEAM), titanium|
|Journal||Modelling and Simulation in Materials Science and Engineering|
Gibson, J.S., Srinivasan, S.G., Baskes, M.I., Miller, R. E, & Wilson, A.K. (2017). A multi-state modified embedded atom method potential for titanium. Modelling and Simulation in Materials Science and Engineering, 25(1). doi:10.1088/1361-651X/25/1/015010