A linear equation, first-order in time, that determines the entire future of an isolated quantum system from the present values of its wave function.
iħ ∂Ψ/∂t = ĤΨ
The same operator Ĥ that generates the motion is the observable whose eigenvalues are the energies a measurement can return.
Schrödinger obtained the equation in 1926. When the potential does not depend on time the solutions of definite energy separate as ψ(x) e^{-iEt/ħ}, leaving the eigenvalue problem Ĥψ = Eψ whose Coulomb eigenfunctions reproduce the discrete spectrum of hydrogen.