Self-trapping phase diagram for the strongly correlated extended Holstein-Hubbard model in two-dimensions

• Published in: The European physical journal. B, Condensed matter physics Vol. 87; no. 7
• Main Authors: Sankar, I. V., Chatterjee, Ashok
• Format: Journal Article
• Language: English
• Published: Berlin/Heidelberg Springer Berlin Heidelberg 01.07.2014; Springer
• Subjects: Analysis; Complex Systems; Condensed Matter Physics; Fluid- and Aerodynamics; Physics; Physics and Astronomy; Regular Article; Solid State Physics; Superconductors; Solid State and Materials
• ISSN: 1434-6028; 1434-6036
• DOI: 10.1140/epjb/e2014-50146-9

The two-dimensional extended Holstein-Hubbard model is investigated in the strong correlation regime to study the nature of self-trapping transition and the polaron phase diagram in the absence of superconductivity. Using a series of canonical transformations followed by zero-phonon averaging the extended Holstein-Hubbard model is converted into an effective extended Hubbard model which is subsequently transformed into an effective t - J model in the strong correlation limit. This effective t - J model is finally solved using the mean-field Hartree-Fock approximation to show that the self-trapping transition is continuous in the anti-adiabatic limit while it is discontinuous in the adiabatic limit. The phase diagrams for the localization-delocalization transition, namely the phase line and the phase surface separating the small polaron and large polaron states are also shown.