Correlations in Novel Quantum Materials 2022 (CNQM2022)

Session

Dynamical Response and Vertex Functions

20 Jun 2022, 13:50

2D5 (Max Planck Institut für Festkörperforschung)

58. Computing Local Multipoint Correlators Using the Numerical Renormalization Group

Jan von Delft (LMU München)

20/06/2022, 14:00

Keynote Talk / Invited Talk

Local three- and four-point correlators yield important insight into strongly correlated systems and have many applications. However, the nonperturbative, accurate computation of dynamical multipoint correlators is challenging, particularly in the real-frequency domain for systems at low temperatures. We have developed generalized spectral representations for multipoint correlators, and a...

57. Spectral Representations for Multipoint Correlators and the Real-Frequency Four-Point Vertex

Fabian Kugler (Rutgers University)

20/06/2022, 14:45

Keynote Talk / Invited Talk

The many-body problem is usually approached from one of two perspectives: the first originates from an action and is based on Feynman diagrams, the second is centered around a Hamiltonian and deals with quantum states and operators. The connection between results obtained in either way is made through spectral (or Lehmann) representations, well known for two-point correlators. We have derived...

51. Fluctuation diagnostics in broken-symmetry phases: Identification of the pairing glue in d-wave superconductors

Alessandro Toschi (GNOI)

20/06/2022, 15:45

Keynote Talk / Invited Talk

In recent years, reliable approaches have been developed [1,2] to unambiguously identify the dominant fluctuations driving the multifaceted phenomena of many-electron physics. Among those, the "fluctuation diagnostics" [3] relies on the possibility of expressing the physical quantity of interest in complementary representations. Hitherto, this scheme has been only applied to normal,...

63. Two-particle self-consistency in diagrammatic extensions of the dynamical mean field theory

Georg Rohringer (GNOI)

20/06/2022, 16:15

Keynote Talk / Invited Talk

In the last 30 years, the dynamical mean field theory (DMFT) has developed to a standard tool for the theoretical description of strongly correlated electron systems. It self-consistently maps a lattice Hamiltonian onto an impurity problem which can be solved exactly via exact diagonalization or Quantum Monte Carlo methods. In this way, all purely local correlation effects in the system are...