My Talk at ETSF 2022 on Density Functional Embedding Theory for Excited States
Channel: Phys Whiz
Date: 2022-12-31

This talk was given at ETSF 2022 (https://workshop.etsf.eu/) on June 14, 2022

I present some of my PhD work in this talk.

The work has also been published in Journal of Chemical Theory and Computation.
Read it here: https://pubs.acs.org/doi/10.1021/acs.jctc.2c00380

Abstract:
One of the main challenges in the application of accurate wavefunction theory (WFT) methods for hybrid systems, such as solvated molecules or molecules adsorbed on a surface, is their unfavorable $N^{3-8}$ scaling with system size. An implementation of a density functional theory (DFT)-based embedding framework for the calculation of excited states via WFT methods and real time-time dependent density functional theory (RT-TDDFT) is presented.  The framework allows to partition the density of the total system into subsystem densities: cluster (subsystem of interest) density and environment density (which is kept frozen). The influence of the environment on the cluster is manifested in the form of an embedding potential $v_\mathrm{emb}[\rho^\mathrm{clus}, \rho^\mathrm{env}]$, which is a functional of cluster and environment densities.
The computationally intensive WFT and RT-TDDFT calculations can then be performed using only the cluster basis functions, which significantly reduces the computational time compared to a supermolecular calculation. Various strategies for constructing the embedding potential are analyzed and benchmarked with respect to excited state properties. It is found that embedding potentials containing the non-additive kinetic energy density functionals (nadd-KEDFs) offer reasonable accuracy and excellent speed-up of WFT calculations for weakly interacting systems such as solvated molecules. Furthermore, a comparison of projection operator and nadd-KEDF based embedding schemes for RT-TDDFT calculations is shown for various test systems.
All the methods are implemented within the TURBOMOLE program package.