Physica B 353 (2004) 201–204 Phonon Raman linewidth in correlated metals A.K. Verma, D.M. Gaitonde à , R.S. Rao, B.K. Godwal High Pressure Physics Division, Bhabha Atomic Research Centre, Trombay, Mumbai 400085, India Received 6 August 2004; accepted 28 September 2004 Abstract We calculate the phonon linewidth of a Raman-active zone centre phonon in a correlated metal. The correlated metal is described by the half-filled single-band Hubbard model on a hypercubic lattice in d ¼1: The electronic self-energy and Green function are determined within the dynamical mean field theory (DMFT) for various values of U in the metallic regime and then used to calculate the phonon linewidth. We consider only the lowest order contribution corresponding to a process in which the phonon decays into a particle–hole pair. At weak correlation we find that the electronic contribution to the phonon linewidth is negligibly small but it grows with increasing correlation strength and then reaches a maximum before showing a decrease. r 2004 Elsevier B.V. All rights reserved. PACS: 71.10.Fd; 71.27.þa; 78.30.j Keywords: Correlated electrons; Phonons; Raman scattering An understanding of strongly correlated metals has been a long-standing problem in condensed matter physics. The Hubbard model is generally believed to be the minimal model that captures the essential physics of electronic correlation. At half- filling this model is believed to undergo a Mott metal–insulator transition [1] and experimentally too there are compounds like V 2 O 3 [2] whose phase diagram exhibits the qualitative physics expected from the Hubbard model. There have been several theoretical attempts at deriving the phase diagram of the Hubbard model starting with the early work of Hubbard [3]. Over the past decade these efforts have intensified with the discovery of high-temperature superconductivity in the cuprates [4] and Anderson’s suggestion [5] that the cuprates are doped Mott insulators whose properties are well described by the two-dimen- sional Hubbard model. Some years ago Metzner and Volhardt [6] introduced the infinite-dimensional limit of the Hubbard model as a non-trivial limit which manages to capture many aspects of the physics of correlated electron systems in d ¼ 3: This ARTICLE IN PRESS www.elsevier.com/locate/physb 0921-4526/$ - see front matter r 2004 Elsevier B.V. All rights reserved. doi:10.1016/j.physb.2004.09.094 à Corresponding author. Tel.: +91 22 25593750; fax: +91 22 25505151. E-mail address: dgaitonde@yahoo.com (D.M. Gaitonde).