Variational study of Mott transition by means of Drude weight and superfluid density

S. Tamura, H. Yokoyama

Research output: Contribution to journalConference articlepeer-review

3 Citations (Scopus)


To distinguish a metal from an insulator, the Drude weight (D, zero-frequency component of conductivity) is a useful measure, as Kohn pointed out long ago: D>0(=0) for a metal (insulator). Later, Millis and Coppersmith showed that a variational wave function Ψ Q in which the key ingredient for a Mott transition (a doublon-holon binding effect) is introduced exhibits D> 0 (metallic) even for sufficiently large correlation strength, namely, a Mott transition is absent from Ψ Q. In contrast, variational Monte Carlo studies using Ψ Q confirmed, by studying relevant quantities such as doublon density d and a superconducting correlation function Pd, that Ψ Q undoubtedly raises a Mott transition. This contradiction has been a long-standing perplexing problem. We definitely settle this problem by adding to Ψ Q a configuration-dependent phase factor Pθ, which has been hitherto overlooked. This factor appropriately picks out a negative counterpart in D for insulators, so that vanishes. Because Pθ does not affect the quantities such as d and Pd, the previous results of Ψ Q on the Mott transition remain intact for Pθ Ψ Q.

Original languageEnglish
Pages (from-to)5-8
Number of pages4
JournalPhysics Procedia
Publication statusPublished - 2013
Event25th International Symposium on Superconductivity, ISS 2012 - Tokyo, Japan
Duration: 2012 Dec 32012 Dec 5


  • Drude weight
  • Hubbard model
  • Variational Monte Carlo

ASJC Scopus subject areas

  • Physics and Astronomy(all)


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