In
physics and
quantum chemistry, specifically
density functional theory, the
Kohn–Sham equation is the
Schrödinger equation of a fictitious system (the "
Kohn–Sham system") of non-interacting particles (typically electrons) that generate the same
density as any given system of interacting particles. The Kohn–Sham equation is defined by a local effective (fictitious) external potential in which the non-interacting particles move, typically denoted as
vs(
r) or
veff(
r), called the
Kohn–Sham potential. As the particles in the Kohn–Sham system are non-interacting fermions, the Kohn–Sham wavefunction is a single
Slater determinant constructed from a set of
orbitals that are the lowest energy solutions to