The Hubbard model description of the TCNQ related singular features in photoemission ofTTF-TCNQ

Abstract

In this paper we use the pseudofermion dynamical theory (PDT) to studythe singular spectral features due to one-electron removal within theone-dimensional Hubbard model. The PDT reveals that in the whole(k, ω)-plane such features are of the power-law type and correspond to well defined lines of threetypes: charge singular branch lines, spin singular branch lines and border lines. One of ourgoals is the study of the momentum and energy dependence of the distribution of thespectral weight in the vicinity of such lines. We find that the charge and spinbranch lines correspond to the main tetracyanoquinodimethane (TCNQ) peakdispersions observed with angle-resolved photoelectron spectroscopy in the quasi-1Dorganic conductor tetrathiafulvalene-tetracyanoquinodimethane (TTF-TCNQ).Our expressions refer to all values of the electronic density and on-site repulsionU. The weight distribution in the vicinity of the singular spectral lines is fully controlled bythe overall pseudofermion phase shifts. Moreover, the shape of these lines is determinedby the bare-momentum dependence of the pseudofermion energy dispersions.