Psi-k - Ab initio (from electronic structure) calculation of complex processes in materials

Working Group 1 - GW Method (WG1 Web pages)

Angel Rubio, U Pais Vasco, Spain

The GW is a perturbation approach, that improves both the LDA total energy and its excitation spectrum. The ground state energies obtained within the GW are a substantial improvement on the LSD however not as accurate at the QMC methods but substantially faster to calculate. New approaches for total energy calculations based on many-body perturbation theory have been developed recently. They can be extended to compute forces which forms an exciting development. The working group will pursue improved calculation of activation barriers in catalysis on a surface (even for biological systems). Also, with time- and energy-resolved spectroscopies in mind, it will assess and derive potential-energy surfaces for dynamics of photoexcited molecules near solid surfaces.

The GW method itself will be developed through the theoretical and practical study of the problems related to the self-consistency, vertex corrections, correlation functionals, description of superconductivity. The GW technique will be compared with approaches based on response-function description of the correlation energy as done, for example, within TDDFT.

The majority of the applications of the GW method are in the calculation of the excitation spectrum. One-particle calculations are performed for the quasi-particle spectrum, including lifetimes and image states. Calculations will be performed for technologically important materials such as nanostructures and complex compounds of transition metal oxides. Two-particle excitations are evaluated with the Bethe-Salpeter method and comprise the study of spectroscopies such as electron energy loss, time-resolved two-photon emission. Similarly studies will be conducted within TDDFT schemes recently developed that handle electron-hole interactions absent in the standard TDLDA when it is applied to extended systems.

It is expected that members of the GW method working group will have fruitful collaborations with the QMC and the DMFT working groups.

MEMBERS OF THE WORKING GROUP [14 members]

including some people working on TD DFT and related approaches for excited states, not covered by WG2 or WG3.