Simulation of multi-atomic interactions in H–O–W system with the MD code CADAC

For future tokamak reactors, chemical erosion of tungsten armour surfaces under impact of hot deuterium–tritium plasma that contains impurities, for instance oxygen, is an important issue. Oxygen can form volatile molecular complexes OxWy at the surface, and the retained H-atoms form the volatile complexes HxOy, which mitigates the erosion (H states for hydrogen isotopes). The plasma impact can substantially destroy the complexes. cribe this H–O–W system, the molecular dynamics (MD) code CADAC was earlier developed using only pair–atomic interactions. Now CADAC is extended for multi-body forces to simulate molecular organization of atoms near the tungsten surface. The approach uses the Abellʹs model of empirical bond-order potentials in addition combined, for the first time, with a valence concept. CADAC simulates chemical features using atomic valences and the Morse potentials. The new model is introduced and model parameters are estimated.