- We performed non-empirical simulations of the properties of the tungsten Σ3(1 1 1) grain boundary (GB) with boron atom and demonstrated the influence of many-body interactions on the resistance of the GB with respect to sliding. We also studied the propagation of relaxation in the vicinity of the GB. The many-body interatomic potentials used in these simulations were obtained from ab initio total energy calculations with the use of the recursion procedure. At each step of the slip process the equilibrium positions of the atoms nearby GB were calculated with the generalized simulated annealing technique. The relaxation of atoms in different planes was calculated. It was shown how the slip shifts influence the penetration of the elastic field inside the grain.