Berlin 2005 – wissenschaftliches Programm
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TT: Tiefe Temperaturen
TT 16: Posters Correlated Electrons, Measuring Devices, Cryotechnique
TT 16.7: Poster
Samstag, 5. März 2005, 11:00–16:30, Poster TU C
Tomonaga-Luttinger-liquid parameter from density-matrix renormalization group calculations — •Satoshi Ejima1, Florian Gebhard1, and Satoshi Nishimoto2 — 1Fachbereich Physik, Philipps-Universität Marburg — 2Institut für Theoretische Physik, Universität Göttingen
In a Tomonaga-Luttinger-liquid the density of states vanishes algebraically at the Fermi energy. The corresponding exponent α can be observed experimentally in quasi one-dimensional systems, e.g., in single-walled carbon nanotubes and other organic conductors. Experimental results, α>1, deviate substantially from those for simple one-dimensional models such as the Hubbard model where α≤ 1/8. More realistic models contain nearest-neighbor interactions which strongly modify the critical exponent. However, the calculation of α for the extended Hubbard model is very difficult because no exact solution exists.
We use the density-matrix renormalization group (DMRG) method to calculate numerically the density-density correlation function for large systems with open boundary conditions. We extract α from the large-distance behavior of the density-density correlation function. We test our approach against analytical results for the one-dimensional Hubbard model and the XXZ Heisenberg chain and find an excellent agreement. As an application we calculate α in the extended Hubbard model. We show that a lightly doped charge-density-wave insulator can exhibit α>1.