A comparison of interatomic potentials for modeling tungsten–hydrogen–helium plasma–surface interactions

Abstract

Article history:Available online xxxx a b s t r a c tWe compare the hydrogen and helium clustering characteristics of three interatomic potential energy models intended for simulation of plasma-facing materials for fusion applications. Our simulations compare a Finnis-Sinclair potential and two different Tersoff-style bond order potentials created by Juslin et al. (2005) and Li et al. (2011), respectively, with respect to both helium and hydrogen clustering behavior in tungsten. We find significant differences between the Juslin and Li potentials in terms of both hydrogen and helium clustering behavior as well as the spatial distribution of hydrogen below the surface. These simulations are an important test on the road to more accurate models of gas clustering and surface evolution of tungsten divertors in ITER and other plasma devices.

Data-driven material models for atomistic simulation

“…The left and right panels show the percent errors with respect to the DFT predictions for the pure-W and pure-Be SNAP potentials, respectively. In both cases, the corresponding results for an empirical potential is shown (EAM 32,59 for W and BOP 33 for Be). One of the primary flaws of the W-EAM potential 59 was the prediction of an attractive divacancy binding energy at the nearest neighbor position, whereas DFT predicts 60 a mild (0.12 eV) repulsive energy for this defect configuration.…”

“…However, there are not many IAP developed for tungsten and beryllium and their accuracy is limited for this particular application. While many potentials exist for tungsten 32 , only one exists for modeling W and Be 33 , which is a Tersoff style bond order potential (BOP) 10 . This potential has been used to study both beryllium implantation in tungsten 34 and mixed beryllium-deuterium implantation in tungsten 35 .…”

Recent advances in modeling and simulation of the exposure and response of tungsten to fusion energy conditions

“…The key input to MD is the interatomic potential, which, for the sake of computational speed, is typically formulated semi-empirically based on input from quantum mechanical calculations and/or experimental data. In the case at hand, much effort has been devoted to developing interatomic potentials for the W-He-H-Be system and any of their pairwise variants [65][66][67]. For bulk neutron damage calculations, it is of interest to develop W-Re, W-Os, and possibly W-Pt potentials (as well as other transition metals) as a result of significant neutron induced transmutation (to be discussed later), but very little research has been directed to these systems as of yet, with efforts primarily focused on first principles calculations of defects and solute complexes in binary W alloys.…”

Challenges and opportunities of modeling plasma–surface interactions in tungsten using high-performance computing

“…Two recent potentials have been fit to describe W-H with a Tersoff-type three-body interaction potential, one by Juslin and co-workers [62] and another by Li and co-workers [63]. As noted in a companion paper in these proceedings [64], the two potentials predict very different hydrogen behavior near tungsten surfaces and in the presence of helium clusters. The energetics of small He-H clusters in bulk tungsten have been determined by the DFT calculations of Becquart and co-workers [65,66], as well as by You and co-workers [67]; and the results of the Juslin potential [60] semi-quantitatively capture the trends exhibited by the binding energies predicted by Becquart and Domain [65].…”