Impurity solvers

Accurate and efficient solutions of multi-orbital impurity problems is key to the success of LDA+DMFT methods (or cluster-DMFT). There are many issues to discuss there, e.g:

• How to improve the numerical efficiency of QMC solvers ?

• NCA: virtues and drawbacks Recent improvements of NCA.
• Approximate efficient solvers: low-energy slave bosons, high-energy equations of motion, etc...

• Constraints and cross-checks on impurity solvers: sum rules, weight of Hubbard bands in the multi-orbital case, etc...

• New algorithms ?

There are many other technical points to be discussed: k-sums, analytic continuation of QMC data, etc...