On the applicability of hybrid functionals for predicting fundamental properties of metals

• Limitations of hybrid functional in describing metallic properties are discussed.
• The use of hybrid functional results in greatly suppressed density of states at EF.
• Erroneously enhanced electron–phonon coupling and lattice stability is discussed.
• Hybrid functionals overestimate local magnetic moments of transition metals.
• Our work calls for a thorough re-evaluation of the hybrid functional approach.

The repercussions of an inaccurate account of electronic states near the Fermi level by hybrid functionals in predicting several important metallic properties are investigated. The difficulties include a vanishing or severely suppressed density of states (DOS) at EF, significantly widened valence bandwidth, greatly enhanced electron–phonon (el–ph) deformation potentials, and an overestimate of magnetic moment in transition metals. The erroneously enhanced el–ph coupling calculated by hybrid functionals may lead to a false prediction of lattice instability. The main culprit of the problem comes from the simplistic treatment of the exchange functional rooted in the original Fock exchange energy. The use of a short-ranged Coulomb interaction alleviates some of the drawbacks but the fundamental issues remain unchanged.