Berlin 2018 – wissenschaftliches Programm

Bereiche | Tage | Auswahl | Suche | Aktualisierungen | Downloads | Hilfe

TT: Fachverband Tiefe Temperaturen

TT 15: Dual-Method Approaches to Quantum Many-Body Systems I

TT 15.7: Vortrag

Montag, 12. März 2018, 16:30–16:45, H 0104

Effective models for correlated systems: effects of basis orthogonalization — •Qian Zhang and Erik Koch — Institute for Advanced Simulation, Forschungszentrum Jülich, 52428 Jülich, Germany

Setting up a many-body Hamiltonian requires choosing an orbital basis. Starting from atomic orbitals we have to deal with the non-orthogonality of the basis functions on different sites. We demonstrate the effects arising from orthogonalization on the example of the Hubbard dimer. First we study the change in hopping matrix elements with the bond length for the hydrogen molecule ion. Then we analyze the change in Coulomb matrix elements for the hydrogen molecule. In particular, we investigate how orthogonalization changes the on-site interaction as well as the direct and the exchange contributions to the long-range Coulomb terms. Finally, we discuss how the Coulomb tensor transforms under general (i.e. non-unitary) basis changes.