Semiclassical electron density from ODE shooting method
Thomas-Fermi ODE: φ'' = φ^(3/2)/√x. Boundary conditions: φ(0)=1, φ(∞)=0. Electron density: n(r) = Z/r · (Z^(1/3)·φ(r)/a₀)^(3/2) × (1/3π²)(2me/ℏ²)^(3/2). Solved by shooting.