  The interaction of vacancy with dislocations in Al is studied using the
Semidiscrete Variational Peierls-Nabarro model with ab initio determined gamma
surface. For the first time, we confirm theoretically the so-called vacancy
lubrication effect on dislocation motion in Al, a discovery that can settle a
long-standing controversy in dislocation theory for fcc metals. We provide
insights on the lubrication effect by exploring the connection between
dislocation mobility and its core width. We predict an increased dislocation
splitting in the presence of vacancy. We find that on average there is a weak
repulsion between vacancies and dislocations which is independent of
dislocation character.
