CASUS Institute Seminar, Abhisek Ghosal Postdoctoral researcher, Schatz Group, Northwestern University, United States
Abstract of the talk// Negative ion resonances, which temporarily bind one or more extra electrons, are found in processes such as dissociative recombination during plasma formation, molecules adsorbed on metal surfaces, the scattering of hot electrons in plasmons, and even in biological molecules like DNA, where they can cause damage in cells. Theoretically, negative ion resonances belong to a special class of open-quantum system problems, where the system is embedded in the continuum. This poses a fundamental challenge to density functional theory (DFT)-based methods due to the unbound nature of resonances. In this presentation, I will discuss a new theoretical framework—complex density functional theory 1—and the underlying assumptions required for combining real Hermitian nonlocal exchange-correlation potentials with complex local potentials.
This new method is capable of treating both continuum and nonlocal correlation effects simultaneously. We observed remarkable improvements in the description of negative ion resonances compared to exact exchange and static polarization-based methods, and it is highly competitive with the state-of-the-art EOM-EA-CCSD method. I will also discuss the use of low-scaling approximations and their effectiveness in investigating the effect of the chemical environment on negative ion resonances. This work provides a practical solution to the long-standing issue of characterizing negative ion resonances within the DFT framework in a non-empirical manner.
Abhisek will give an online seminar. However, as the event is organized in a hybrid format that includes a videoconferencing tool by Zoom Inc., people interested in the topic have the chance to also join the talk remotely. Please ask for the login details via contact@casus.science.