What exactly is the ground state? This concerns the applicability of mean field approaches to such a system: quantum fluctuations 13 not included in the Hartree–Fock (HF) approximation may be significant because gap states are no longer empty.
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What exactly is the ground state? This concerns the applicability of mean field approaches to such a system: quantum fluctuations 13 not included in the Hartree–Fock (HF) approximation may be significant because gap states are no longer empty.