Ab initio based empirical potential applied to tungsten at high pressure

Abstract

Density-functional theory forces, stresses and energies comprise a database from which the optimal parameters of a spline-based empirical potential combining Stillinger-Weber and modified embeddedatom forms are determined. Accuracy of the potential is demonstrated by calculations of ideal shear, stacking fault, vacancy migration, elastic constants and phonons all between 0 and 100 GPa. Consistency with existing models and experiments is demonstrated by predictions of screw dislocation core structure and deformation twinning in a tungsten nanorod. Lastly, the potential is used to study the stabilization of fcc tungsten at high pressure.

Atomistic investigation of the impact of phosphorus impurities on the tungsten grain boundary decohesion

“…For the former slip system it is found that the tendencies predicted by DFT are captured by the empirical potential. For the GSFE associated with {112}⟨111⟩ slip, we note that the peak of the GSFE curve derived from DFT is slightly perturbed to an off-centre position, which is in accordance with previous DFT results in [40,79]. Although our potential does not produce such significant asymmetric profile, the peak energies of the potential match the DFT data well, which suggests that even though the binary potential was not explicitly fitted for it, it captures the impact of impurities on slip resistance.…”

Improved embedded-atom model potentials of Pb at high pressure: application to investigations of plasticity and phase transition under extreme conditions

“…Reproducing the experimental phenomena at high pressure from atomic simulations is a challenge because of the accuracy, as well as computation efficiency, of present potential models, and construction procedures. Still, based on semi-empirical potential models, some well transferable interatomic potentials of metals are developed for high pressure applications, for example, simulating deformation twinning in tantalum [19] and tungsten [20], as well as phase transition in iron [21,22]. In this work, new interatomic potentials of Pb are developed and employed to simulate the dislocation-mediated plasticity, phase transition and melting under ramp compressions.…”

Atomistic Modelling of All Dislocations and Twins in HCP and BCC Ti

“…Attempts are being made to fit new interatomic potentials with the correct partial core structures and energy ordering on the pyramidal I narrow plane, but success has not been achieved so far. We are unaware of any interatomic potential [38,[84][85][86][87][88][89][90] which exhibits all of the correct core structures of the screw a dislocation in Ti. The current simulations thus demonstrate qualitative features of the glide behaviour of the screw a dislocation.…”