Chebyshev expansion for impurity models using matrix product states

Autor(en)

Martin Ganahl, Patrik Thunstroem, Frank Verstraete, Karsten Held, Hans Gerd Evertz

Abstrakt

We improve a recently developed expansion technique for calculating real-frequency spectral functions of any one-dimensional model with short-range interactions, by postprocessing computed Chebyshev moments with linear prediction. This can be achieved at virtually no cost, and in sharp contrast to existing methods based on the dampening of the moments, improves the spectral resolution rather than lowering it. We validate the method for the exactly solvable resonating level model and the single impurity Anderson model. It is capable of resolving sharp Kondo resonances, as well as peaks within the Hubbard bands when employed as an impurity solver for dynamical mean-field theory. Our method works at zero temperature and allows for arbitrary discretization of the bath spectrum. It achieves similar precision as the dynamical density matrix renormalization group, at lower cost. We also propose an alternative expansion, of 1−exp(−τH) instead of the usual H, which opens the possibility of using established methods for the time evolution of matrix product states to calculate the spectral functions directly.

Organisation(en)

Quantenoptik, Quantennanophysik und Quanteninformation

Externe Organisation(en)

Technische Universität Wien, Ghent University , Technische Universität Graz

Journal

Physical Review B

Band

90

Anzahl der Seiten

12

ISSN

1098-0121

DOI

https://doi.org/10.1103/PhysRevB.90.045144

Publikationsdatum

07-2014

Peer-reviewed

Ja

ÖFOS 2012

103015 Kondensierte Materie, 103025 Quantenmechanik

Schlagwörter

Link zum Portal

https://ucrisportal.univie.ac.at/de/publications/f9aa7dfe-71e7-4644-aa09-d17f9b943094