Recent content by theochem

Dear all, There is a definition of current-density operator, and the form is as follows: j(r)=1/2iƩ[∇lδ(r-rl)+δ(r-rl)∇l] I cannot understand this form, because i think ∇ operator and δ operator are commutable. Another form of current-density operator can be found from this website...