Dresden 2006 – wissenschaftliches Programm
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TT: Tiefe Temperaturen
TT 4: Correlated Electrons: Quantum Impurities, Kondo Physics
TT 4.5: Vortrag
Montag, 27. März 2006, 12:15–12:30, HSZ 301
DMRG meets NRG — •Andreas Weichselbaum1, Frank Verstraete2, Ulrich Schollwöck3, J. I. Cirac4, and Jan von Delft1 — 1Physics Department, Arnold Sommerfeld Center for Theoretical Physics, and Center for NanoScience, Ludwig-Maximilians-Universität München, 80333 München, Germany — 2Institute for Quantum Information, Caltech, Pasadena, US. — 3Institut für Theoretische Physik C, RWTH-Aachen, D-52056 Aachen, Germany — 4Max-Planck-Institut für Quantenoptik, Hans-Kopfermann-Str. 1, Garching, D-85748, Germany
We present a unified framework of renormalization group methods, including Wilson’s numerical renormalization group (NRG) and White’s density-matrix renormalization group (DMRG), within the language of matrix product states. This allows to improve over Wilson’s NRG for quantum impurity models by a variational method optimal in this framework. We illustrate it for the single-impurity Anderson model; moreover we use a variational method for evaluating Green’s functions. The proposed method is more flexible in its description of off-resonance spectral properties, opening the way to time-dependent, out-of-equilibrium impurity problems. It also substantially improves computational efficiency for one-channel impurity problems, suggesting linear scaling of complexity for n-channel problems.