As a result, we find: j ( x ) ≡ ≡ 2 ℑ ℑ { Ψ Ψ ¯ ¯ ( x ) i v Ψ Ψ ( x ) } = 2 ℑ ℑ { Ψ Ψ ¯ ¯ ( x ) ( ( − − S Ψ Ψ ) ( x ) + ( S ∗ ∗ Ψ Ψ ) ( x ) ) } = 2 ℑ ℑ { Ψ Ψ ¯ ¯ ( x ) ( − − Ψ Ψ ( x − − 1 ) + Ψ Ψ ( x + 1 ) ) }