On the binding of nanometric hydrogen–helium clusters in tungsten

Abstract

In this work we developed an embedded atom method potential for large scale atomistic simulations in the ternary tungsten-hydrogen-helium (W-H-He) system, focusing on applications in the fusion research domain. Following available ab initio data, the potential reproduces key interactions between H, He and point defects in W and utilizes the most recent potential for matrix W. The potential is applied to assess the thermal stability of various H-He complexes of sizes too large for ab initio techniques. The results show that the dissociation of H-He clusters stabilized by vacancies will occur primarily by emission of hydrogen atoms and then by break-up of V-He complexes, indicating that H-He interaction does influence the release of hydrogen.

Interaction of hydrogen with dislocations in tungsten: An atomistic study

“…9 for comparison. The calculated value of E m is 0.23 eV and is lower than the experimentally obtained value, but is consistent with the values of the migration barrier between tetrahedral positions, which is 0.21 eV as predicted by the potential [11], and 0.2 eV as obtained by ab initio in [16]. Clearly, the diffusivity of H attached to the dislocation line is much higher than the bulk diffusivity, especially at low temperatures as can be seen in Fig.…”

“…[9,10], and recently derived embedded atom method potentials by Bonny et al [11]. On the basis of the obtained results we can draw the following conclusions:…”

“…There were two different versions of the EAM potential, referred to as "EAM1" and "EAM2" in [11]. The BOP potential, developed in [9,10], was fitted to the H interaction with point defects in W. It reproduces very well H-W molecules and geometry of H-vacancy system (i.e.…”

“…The choice was made after critical review of 19 different EAM potentials given in [13]. For the EAM1 potential, emphasis was put on a quantitative reproduction of ab initio data for the binding between H-H, He-He and H-He pairs [11]. The off-center position of a H atom in a vacancy as predicted by DFT [14] was not considered, and therefore both H and He are described by pair potentials only.…”

“…The study is performed using two interatomic potentials, namely: the bond order type potential (BOP) developed by Li et.al. [9,10], and the recently derived embedded atom method (EAM) potential [11]. The results are compared with available ab initio data.…”