Equation Icon  0 0 ψ3 = ψ 4 = 0, (249 ) ∂ ψ02 = 0, (250 ) 0 0 0 ∂ ψ1 = 3σ ψ 2, -- -- -- (251 ) Ψ ≡ ψ02 + ∂2σ-= ψ02 + ∂2σ = Ψ. (252 )