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# Upcoming Webinar: The Random Phase Approximation: A Practical Method Beyond DFT

### Upcoming Webinar

## The Random Phase Approximation: A Practical Method Beyond DFT

Join Professor Georg Kresse in this next UGM webinar presentation:

The random phase approximation (RPA) to the correlation energy and the related GW approximation are among the most promising methods to obtain accurate correlation energy differences and QP energies from diagrammatic perturbation theory at reasonable computational cost, in particular, for solid state systems. The calculations are, however, usually two to three orders of magnitude more demanding than conventional density functional theory calculations. Here, we show that a cubic system size scaling can be readily obtained reducing the computational time by typically one to two orders of magnitude for large systems [1, 2, 3]. Furthermore, the scaling with respect to the number of k points used to sample the Brillouin zone can be reduced to linear order. In combination, this allows accurate and very well-converged single-point RPA and GW calculations, with a time complexity that is roughly on par to self-consistent Hartree-Fock and hybrid functional calculations. Furthermore, the talk discusses the relation between the RPA correlation energy and the GW approximation. It is shown that the GW self-energy is the derivative of the RPA correlation energy with respect to the Green’s function. The calculated self-energy can be used to compute QP-energies in the GW approximation as well as any first derivative of the total energy including interatomic forces. This means that we can now relax atoms and perform molecular dynamics using the RPA and VASP, in the same way as for density functional theory, opening the field of materials simulations to methods beyond density functional theory. Recent advances such as a finite temperature RPA implementation which allows to treat metals using the RPA are also briefly discussed. Finally, applications of the RPA to materials sciences problems are presented.

[1] M. Kaltak, J. Klimés, and G. Kresse, J. Chem. Theory Comput. 10, 2498 (2014). [2] M. Kaltak, J. Klimés, and G. Kresse, Phys. Rev. B 90, 054115 (2014). [3] P. Liu, M. Kaltak, J. Klimés, and G. Kresse, Phys. Rev. B 94, 165109 (2016). [4] J. Klimés, M. Kaltak, E. Maggio, and G. Kresse, J. Chem. Phys. 140, 084502 (2015). [5] B. Ramberger, T. Schäfer, and G. Kresse, Phys. Rev. Lett. 118 106403 (2017). [6] M. Kaltak and G. Kresse, Phys. Rev. B 101, 205145 (2020).

### Biography

Georg Kresse, Univ.-Prof. Dipl.-Ing. Dr. Professor Georg Kresse received his doctoral degree from the Vienna University of Technology in 1993. After his habilitation at the Vienna University of Technology in 2001, he was offered a full professorship by both the University of Oxford and the University of Vienna. In 2007 he accepted the chair for Computational Quantum Mechanics in Vienna. Since 2011 Kresse is a full member of the Austrian Academy of Sciences and since 2012 of the International Academy of Quantum Molecular Sciences. He is the recipient of several awards, including the 2003 "START Grant" of the Austrian Science Fund (FWF), the "Hellmann Preis" of the Internationale Working group for Theoretical Chemistry, and the Kardinal-Innitzer-Preis in 2016. His main research interests are Theoretical Solid State Physics, Surface Sciences and Computational Materials Physics. His work on ab initio density functional theory has shaped the application of density functional theory in materials sciences worldwide. Georg Kresse is the main author and developer of the computer program "VASP" (Vienna ab initio simulation package), which is the most widely used program for quantum mechanical simulations of solids and their surfaces. The three publications on the algorithms implemented in VASP have been cited between 40.000 and 65.000 times each and belong to the 100 most cited research articles ever published. His current work focuses on the precise description of electron interactions in solids and real materials, encompassing modern many body theory, quantum Monte Carlo methods and machine learning. Georg Kresse is the author of more than 400 research articles. With a Web of Sciences h-index of over 105 he is among the most cited physicists.

##### Wednesday October 14: 6:30 am PDT / 9:30 am EDT USA 3:30 pm Europe CEST 7:00 pm India (IST) 9:30 pm China (CST) 10:30 pm Japan (JST) Wednesday October 14: 9:30 am PDT / 12:30 pm EDT USA 6:30 pm Europe CEST 10:00 pm India (IST)

Professor Kresse’s lecture will be presented at two separate times on October 14 to accommodate schedules worldwide. Choose the meeting time that is most convenient for you.

This year's UGM plenary speaker presentations are open to everyone!

If you have any questions, please contact ugm@materialsdesign.com.