J. Phys. IV France 114 (2004) 45
DOI: 10.1051/jp4:2004114008

New method for evaluation of finite-energy few-electron spectral function expressions

J.M.P. Carmelo¹, K. Penc², P.D. Sacramento³ and R. Claessen<sup>4

1</sup>  GCEP-Center of Physics, University of Minho, Campus Gualtar, 4710-057 Braga, Portugal
    e-mail: carmelo@fisica.uminho.pt
²  Research Institute for Solid State Physics and Optics, 1525 Budapest, P.O. Box 49, Hungary
    e-mail: penc@szfki.hu
³  Departamento de Física and CFIF, Instituto Superior Técnico, 1049-001 Lisboa, Portugal
    e-mail: pdss@cfif.ist.utl.pt
⁴  Experimentalphysik II, Universität Augsburg, 86135 Augsburg, Germany
    e-mail: claessen@physik.uni-augsburg.de

Abstract
We present a method for the calculation of few-electron spectral functions of the one-dimen- sional Hubbard model which relies on a pseudofermion description introduced recently in Ref. [6]. The spectral functions are expressed as a convolution of pseudofermion dynamical correlation functions. Our general method involves the direct evaluation of the matrix elements of pseudofermion operators between the ground state and the excited states. We briefly discuss the application of our general method to the study of the unusual finite-energy spectral properties observed in the quasi-one-dimensional organic conductor TTF-TCNQ. Key words. correlation effects - spectral properties - organic conductors

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