The total energy is determined by approximate solutions of the time-dependent Schrödinger equation , usually with no relativistic terms included , and by making use of the Born-Oppenheimer approximation , which allows for the separation of electronic and nuclear motions , thereby simplifying the Schrödinger equation .
The Born-Oppenheimer approximation , which allows for the separation of electronic and nuclear motions , can simplify the Schrödinger equation .