STFC Daresbury Laboratory
3 1/2 days from the afternoon of the 16th through the 19th of May, 2017
To register please visit https://questaalworkshop.eventbrite.co.uk
This course will provide tutorials for both the theory of, and how to use, an all-electron code that implements both density functional theory and GW/quasi-particle self-consistent GW (QSGW) theory. The density-functional part is implemented with full potential generalization of the linearized muffin-tin orbitals (LMTO) theory, or LMTO+LAPW combined. We will also present a recent implementation of Dynamical Mean Field theory through an interface to Kristjan Haule’s implementation of Continuous time Quantum Monte Carlo (CTQMC). The interface can connect to CTQMC either with LDA or with QSGW; see this paper.
Questaal also includes a number of extensions, such as modules to calculate transport properties, magnetic properties, optical properties, etc. There is an implementation of the coherent potential approximation, making it possible to address systems with chemical or spin disorder within the LDA. Questaal also has a principal layer Green’s technique to transport though nonperiodic, layered systems. Some of these extensions will be presented in the tutorials.
The QSGW package contains an implementation in an all-electron context, GW theory based on the LDA, and also the quasi-particle self-consistent GW theory. The latter goes beyond standard GW theory as it does not use density functional theory as a reference, but a self-consistently determined non-interacting system which is by construction the optimal starting point for many body perturbation theory. QSGW is more reliable and universally applicable than standard density-functional based GW. Participants will have practical tutorials to gain experience in how to use the codes and analyse results. We will present several examples where QSGW predicts properties in cases where LDA based GW fares poorly, and discuss how DMFT, in a nonperturbative context, and ladder diagrams in many body perturbation theory, can help to surmount these limitations.
The course will last for 3 1/2 days. The mornings will consist of formal lectures wth theory by van Schilfgaarde and Gruening, followed by tutorials organised by developors or users of the code. The afternoon sessions are dedicated to practical exercises with the code. We plan the following schedule:
We cannot cover any transportation cost, but food and accommodation for the duration of the course will be provided free of charge.