Kohn-Sham Decomposition in Real-Time Time-Dependent Density-Functional Theory: An Efficient Tool for Analyzing...

Area of Science:

• Computational Chemistry
• Materials Science
• Condensed Matter Physics

Background:

• Analyzing electronic excitations is crucial for understanding material properties.
• Kohn-Sham (KS) electron-hole transitions provide a detailed decomposition of electronic excitations.
• Current real-time time-dependent density-functional theory (RT-TDDFT) methods lack efficient KS decomposition analysis compared to linear-response TDDFT.

Purpose of the Study:

• To implement a KS decomposition tool within the RT-TDDFT framework.
• To enable efficient analysis of electron-hole transitions in large systems using RT-TDDFT.
• To investigate plasmon resonances in silver nanoparticles.

Main Methods:

• Developed a KS decomposition tool for local-basis-set RT-TDDFT within the GPAW package.
• The implementation relies on postprocessing readily available data during time propagation.
• Benchmarked the tool on benzene derivatives and applied it to silver nanoparticles (up to Ag561).

Main Results:

• Successfully reconstructed Casida eigenvectors from RT-TDDFT, validating the KS decomposition.
• Analyzed plasmon resonances in icosahedral silver nanoparticles, revealing splitting in smaller clusters.
• Observed the formation of a d-electron-screened plasmon resonance in larger silver nanoparticles.

Conclusions:

• The implemented KS decomposition tool enhances the analytical capabilities of RT-TDDFT.
• This method provides clear insights into the electronic transitions governing plasmon behavior in nanoparticles.
• The findings contribute to a deeper understanding of plasmonics in metallic nanostructures.