Drude and superconducting weights and Mott transitions in variation theory

Shun Tamura, Hisatoshi Yokoyama

Research output: Contribution to journalArticlepeer-review

8 Citations (Scopus)


The Drude weight (D) is a useful measure for distinguishing a metal from an insulator. However, D has not been justifiably estimated using variation theory for a long time, since Millis and Coppersmith [Phys. Rev. B 43, 13770 (1991)] pointed out that the variational wave function ΨQ, which includes the key ingredient (doublon-holon binding effect) for a Mott transition, yields a positive D (namely, metallic) even in the Mott insulating regime. We argue that, to obtain a correct D, an imaginary part must exist in the wave function. By introducing a configuration-dependent phase factor Pθ to ΨQ, Mott transitions are successfully represented by D (D = 0 for U > Uc) for normal and d-wave pairing states; thus, the problem of Millis and Coppersmith is solved. Generally, Pθ plays a pivotal role in describing current-carrying states in the regime of Mott physics. On the other hand, we show using perturbation theory that the one-body (mean-field) part of the wave function should be complex for band insulators such as antiferromagnetic states in hypercubic lattices.

Original languageEnglish
Article number064707
JournalJournal of the Physical Society of Japan
Issue number6
Publication statusPublished - 2015 Jun 15


Dive into the research topics of 'Drude and superconducting weights and Mott transitions in variation theory'. Together they form a unique fingerprint.

Cite this