Brillouin theorem

E675971

Brillouin theorem is a fundamental result in quantum chemistry and Hartree–Fock theory stating that single excitations from a Hartree–Fock ground state do not mix with the ground state and therefore do not lower its energy to first order.

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Statements (43)

Predicate Object
instanceOf result in Hartree–Fock theory
result in quantum chemistry
theorem
alsoKnownAs Brillouin condition NERFINISHED
appliesTo Hartree–Fock ground state NERFINISHED
closed-shell Hartree–Fock solutions
single-determinant wavefunctions
assumes Hartree–Fock orbitals are variationally optimized
the Hartree–Fock determinant is a stationary point of the energy NERFINISHED
category Hartree–Fock method concept
electronic structure theory concept
quantum chemistry theorem
concerns configuration interaction
first-order energy corrections
single excitations
stationary conditions of the Hartree–Fock energy
doesNotHoldIf orbitals are not fully optimized
reference state is not a Hartree–Fock stationary point
energyImplication ground-state energy corrections start from double excitations in many-body expansions
field quantum chemistry
quantum mechanics
theoretical chemistry
holdsFor restricted Hartree–Fock NERFINISHED
unrestricted Hartree–Fock
implies configuration interaction singles (CIS) does not change the Hartree–Fock ground-state energy
correlation energy cannot be recovered from single excitations alone
first-order correction to the Hartree–Fock energy from single excitations is zero
matrix elements between the Hartree–Fock determinant and singly excited determinants vanish
the Hartree–Fock determinant is an eigenfunction of the Fock operator within the space of single excitations NERFINISHED
mathematicalForm ⟨Φ₀|H|Φᵢᵃ⟩ = 0 for all single excitations |Φᵢᵃ⟩ from the Hartree–Fock determinant |Φ₀⟩
namedAfter Léon Brillouin NERFINISHED
relatesTo Brillouin condition NERFINISHED
Fock operator NERFINISHED
Slater determinants NERFINISHED
orbital rotations
states single excitations do not lower the Hartree–Fock ground-state energy to first order
single excitations from a Hartree–Fock ground state do not mix with the ground state to first order
usedIn Møller–Plesset perturbation theory NERFINISHED
analysis of orbital optimization conditions
configuration interaction theory NERFINISHED
coupled-cluster theory
derivation of post-Hartree–Fock methods
yearProposed 1930s

Referenced by (1)

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Léon Brillouin notableConcept Brillouin theorem