Berlin 2005 – wissenschaftliches Programm
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TT: Tiefe Temperaturen
TT 16: Posters Correlated Electrons, Measuring Devices, Cryotechnique
TT 16.64: Poster
Samstag, 5. März 2005, 11:00–16:30, Poster TU C
Dynamic phonons and charge order in a quarter-filled ladder — •T. C. Lang, D. R. Neuber, M. Aichhorn, and H. G. Evertz — Institute for Theoretical and Computational Physics, Graz University of Technology, Petersgasse 16, A-8010 Graz, Austria
We investigate the charge order transition of a quarter-filled extended Hubbard-Holstein ladder at finite temperature as a model for sodium vanadate. Based on the canonical Lang-Firsov transformation of the Hamiltonian, a principle component representation of the phonon degrees of freedom allows us to sample phonon configurations in the framework of determinantal Quantum Monte Carlo much more efficiently than previously possible. The sign problem is moderate in a wide range of model parameters relevant for α′-NaV2O5. Experiments and previous calculations imply great relevance of the lattice coupling to the charge order transition. Low frequency lattice vibrations increase the charge order, accompanied by dynamically produced zig-zag lattice distortions. The single-particle spectral function, spin- and charge-spectra of the ladder in the presence/absence of dynamic phonons are obtained.