Ab initio Density functional theory has been exceedingly successful in the last four decades, however, many problems are difficult to address using local or semi-local approximations for the density functional.
This talk will summarize recent developments to go beyond density functional theory. The considered approaches are usually based on many body perturbation theory and involve two particle properties of the many electron wave function. This allows to account for the non-locality of correlation in an elegant and accurate manner. The talk will try to discuss the underlying principles in a simple and transparent way.
The methods we are currently exploring are the random phase approximation to the correlation energy for fast but often astonishingly accurate predictions [1,2,4,5], and coupled cluster methods, which are shown
to yield chemical accuracy for solids, as well as "exact" solutions of the many electron equation using full configuration interaction methods [3].
[1] J. Harl and G. Kresse, Phys. Rev. Lett. 103, 056401 (2009).
[2] L. Schimka, J. Harl, A. Stroppa, A. Grüneis, M. Marsman, F. Mittendorfer, and G. Kresse, Nature Materials 9, 741 (2010).
[3] George H. Booth, Andreas Grüneis, Georg Kresse, and Ali Alavi, Nature 493, 365-370 (2013).
[4] M. Kaltak, J. Klimes, and G. Kresse, Phys. Rev. B 90, 054115 (2014).
[5] B. Ramberger, T. Schäfer, G. Kresse, Phys. Rev. Lett. 118 106403 (2017)
