Quantum Chemistry

This chapter discusses quantum chemistry. Pretty much all of computational chemistry relies on quantum mechanics in the sense that molecular systems follow the laws of quantum mechanics. But ‘quantum chemistry‘ has a more specific meaning: it is the study of chemistry through the use of approximate solutions to the electronic Schrödinger equation. The chapter describes the background and principles of quantum chemistry, with a focus on the conceptually most important approximate approach, which is Hartree–Fock theory. In principle, the time-dependent Schrödinger equation could be used to predict what happens in chemical reactions. The basic approximation in Hartree–Fock theory is an assumption that electrons move independently of one another throughout the molecular system. The chapter then looks at the calculation of a Hartree–Fock wavefunction.