Schrodinger's Equation
Time-Independent
2mℏ2∇2Ψ+UΨ=EΨ Separation of Variables
In spherical coordinates, the Laplacian expands as:
∇2=r21∂r∂(r2∂r∂)+r2sinθ1∂θ∂(sinθ∂θ∂)+r2sin2θ1∂ϕ2∂2 Assuming Ψ(r,θ,ϕ)=R(r)Y(θ,ϕ) and dividing by RY, the equation separates into independent radial and angular parts:
R1drd[r2drdR]−ℏ22mr2(U(r)−E)=−Y1[sinθ1∂θ∂(sinθ∂θ∂Y)+sin2θ1∂ϕ2∂2Y] Each side equals the same separation constant ℓ(ℓ+1), giving the factored wavefunction:
Ψn,ℓ,m(r,θ,ϕ)=Rn,ℓ(r)Yℓ,m(θ,ϕ) Radial part
Rn,ℓ(ρ)=ρℓe−ρ/2Ln−ℓ−12ℓ+1(na2r) Angular part
Yℓm(θ,ϕ)=4π(ℓ+m)!(2ℓ+1)(ℓ−m)!eimϕPℓm(cosθ) where
ρ=na02Zrcj+1=(j+1)(j+2ℓ+2)j+ℓ+1−ncj Pℓm(x)≡(−1)m(1−x2)m/2(dxd)mPℓ(x)Pℓ(x)≡2ℓℓ!1(dxd)ℓ(x2−1)ℓ *Associated Legendre Polynomials (Pℓm)
The Hydrogen Atom
General Wavefunction
Ψn,ℓ,m(r,θ,ϕ)=(na2)32n(n+ℓ)!(n−ℓ−1)!e−r/na(na2r)ℓ[Ln−ℓ−12ℓ+1(na2r)]Yℓ,m(θ,ϕ) where
Lqp(x)≡(−1)p(dxd)pLp+q(x)Lq(x)≡q!ex(dxd)q(e−xxq) *Associated Laguerre Polynomials (Lqp)
Select a State
Wavefunction
ψ210(r,θ,ϕ)=cosθ(2a02r)e−2a0r32a03π1 Radial Equation
R21(r)=(2a02r)e−2a0r24a031 Angular Equation
Y10(θ,ϕ)=cosθ4π3