j _ = 1 2 i m ( Ψ ∗ ∇ Ψ − Ψ ∇ Ψ ∗ ) {\displaystyle {\underline {j}}={\frac {1}{2{\mathfrak {i}}m}}\left({{\Psi }^{*}}\nabla \Psi -\Psi \nabla {{\Psi }^{*}}\right)}
