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TT: Tiefe Temperaturen

TT 6: Postersitzung I: Josephsonkontakte und SQUIDs, Supraleitung: Theorie, Korrelierte Elektronen, Niederdimensionale Systeme, Magnetotransport, Quantenhalleffekt, Kohlenstoff-Nanoröhrchen, Quantenflüssigkeiten

TT 6.25: Poster

Monday, March 26, 2001, 14:30–17:00, Rang S\ 3

Density-Matrix Renormalization Group in Momentum Space — •Satoshi Nishimoto¹, Eric Jeckelmann¹, Florian Gebhard¹, and Reinhard Noack² — ¹Fachbereich Physik, Philipps-Universität Marburg — ²Institut für Physik, Johannes Gutenberg-Universität Mainz

While a momentum-space Density-Matrix Renormalization Group (DMRG) [1] has the advantage that it can calculate quantities not easily computable with the usual real-space method, such as the momentum distribution and momentum-dependent excitations, it has been less commonly used because Xiang [2] found that in the Hubbard model the accuracy of the momentum-space method breaks down for an interaction U larger than a fraction of the band width W. In contrast to Xiang, we find that the ground-state energy does converge to the exact value for up to U ∼ W. However, the convergence as a function of the number of states kept is slower than the exponential convergence found for many systems in the real-space approach. We also discuss another advantage of the momentum-space method, that it can easily be applied to different non-interacting dispersions corresponding to different lattice geometries and hopping ranges.

[1] Density-Matrix Renormalization, ed. by I. Peschel et al. (Springer Lecture Notes in Physics 528, Springer, Berlin, 1999).

[2] T. Xiang, Phys. Rev. B 53, R10445 (1996); see also T. Xiang and X. Wang in Ref. [1], p. 149.