Doctoral defence in Chemistry -  Aleksei V. Ivanov

The defence will be streamed live

Ph.D. student: Aleksei V. Ivanov

Dissertation title: Calculations of Ground and Excited Electronic States Using Self-Interaction Corrected Density Functionals

Opponents: Dr. Thomas Olsen, Associate Professor at the Department of Physics, Technical University of Denmark
Dr. Andrei Manolescu, Professor at the School of Technology, Department of Engineering, Reykjavik University

Advisor: Dr. Hannes Jónsson, Professor at the Faculty of Physical Sciences, University of Iceland

Doctoral committee: 
Dr. Egill Skúlason, Professor at the Faculty of Industrial Engineering, Mechanical Engineering and Computer Science, University of Iceland
Dr. Elvar Örn Jónsson, Specialist  at the Science Institute, University of Iceland

Chair of Ceremony: Dr. Einar Örn Sveinbjörnsson, Professor and the Head of the Faculty of Physical Sciences, University of Iceland

Abstract:

Direct optimization methods for the calculation of ground and excited electronic states are presented for both total density and orbital-density-dependent functionals. The methods have been developed for various types of basis sets including localized atomic orbitals, plane waves and real space grid. The algorithms have been implemented in combination with the projector-augmented-wave method to represent inner electrons of the atoms. The direct optimization method is shown to be more robust and faster than the conventional self-consistent field approach in calculations of both ground and excited states. An assessment of the Perdew-Zunger self-interaction correction (PZ-SIC) to the energy functional has also been made and its performance compared to the commonly used generalized gradient approximation (GGA). PZ-SIC is found to systematically improve the description of the atomization and ionization energy as well as the band gaps of insulators, but needs to be scaled by a half. PZ-SIC can be especially important for the accurate description of systems containing transition metals as is illustrated by the excellent results obtained for the Mn dimer, a system where results of GGA calculations are qualitatively incorrect. However, PZ-SIC does not substantially improve the excitation energy of small organic molecules as the correction there tends to cancel out when the energy of ground and excited states is compared. The efficient and practical implementation of PZ-SIC presented here paves the way for the development of more accurate orbital-density-dependent functionals.

About the doctoral candidate

Aleksei Ivanov was born in Belarus in 1992 and grew up on the Kamchatka peninsula in Russia’s Far East. For his Bachelor’s degree, he moved to the opposite side of the country to study Theoretical Physics at St. Petersburg State University where he also completed his Master’s degree in close collaboration with Prof. Hannes Jónsson. This collaboration continued into his PhD studies at the University of Iceland in which he developed methods for calculating electronic ground and excited states using self-interaction corrected density energy functionals.