The schrodinger equation in 3D (time independent). Letting Phi = X(x).Y(y).Z(z), and solving as a PDE...... The equation looks pretty much the same except there is a seperate Hamiltonian for each of the Cartesian coordinates x y z. However, the 1/X(x) term etc. really confuses me, I dont know where it comes from. Could someone perhaps explain?? ie. H_x = [-(h^2)/2m].[1/X(x)].[(d^2)X(x)/d(X(x))^2] + V(x) ^^^^ where h is representing h-bar, and d the partial derivative. Cheers guys!!