BCCMS  /  Veranstaltungen  /  2019  /  CECAM CEP  /  Description
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Further Information

1. Introduction/ Motivation

Realistic modeling of materials with strong electron correlations presents one of the central challenges in condensed matter theory to date and hold promises for novel materials developments in the spanning the domains from materials for energy applications to novel high temperature superconductors and topological states of matter. On the theory side, the Hubbard model has been one of the central models to understand various aspects of strongly correlated electrons. It incorporates the competition between kinetic and interaction energy in the most basic way and exhibits phenomena such metal-insulator transitions, magnetism and unconventional superconductivity. However, in particular due to neglecting non-local interactions, links between the Hubbard model and real materials can be ambiguous and the Hubbard model can even qualitatively fail to describing real materials whenever non-local interactions are not efficiently screened. Examples include two-dimensional materials or also generically plasmon dispersions in metals which differ qualitatively in models with or without nonlocal interactions. Most obviously, in insulating systems, where screening is by definition incomplete, and also in systems with different competing types of electronic order prominent non-local interaction effects are expected. Various theoretical approaches from different quantum physics and chemistry communities including different flavours of Quantum Monte Carlo, coupled cluster theories, Configuration interaction expansions, embedding theories, extensions of dynamical mean field theory, related quantum cluster theories as well as renormalization group approaches and diagrammatic perturbation theory have been put forward to address strong electron correlations in presence of non-local interactions. However, our understanding of the electronic structure of these systems is still rather limited as regards electronic phase diagrams, excitation spectra, and excited state dynamics both on the pure model side and particularly when it comes to modelling real materials. The development of next-generation realistic many-body computational tools which are fast, reliable and are able to describe non-trivial quantum states of real materials requires clarification how non-local interactions affect the electronic properties of correlated electron systems. This workshop shall foster a clear understanding of merits and shortcomings of the different simulation methods currently under development by bringing together the respective scientific communities from physics and chemistry and set the stage for the development of novel simulation tools for real materials featuring correlated electrons.

2. Objectives

The proposed workshop should become a forum to brainstorm ideas about solutions to correlated-electron problems, particularly in presence of non-local interactions, and to identify new directions for many-body method development and challenging applications. In this way, we hope to create an “exchange mechanism” to unite a core of developers in an interactive environment to initiate design of a new generation software tools for many-body quantum modelling from model systems to real materials. To this end, this workshop brings together people from different correlated electron communities (i.e. solid state physics, computational material science and quantum chemistry) to discuss possible synergies and new ideas in quantum many-body methods. Different methods, their merits and shortcomings shall be carefully discussed and benchmarked. Prospects of method unifications to approach the challenging problem of electron correlations in systems with non-local interactions shall be analysed.

3. References

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