Orbital-free methods for plasmonics: Linear response.

Area of Science:

• Computational Nanoscience
• Quantum Chemistry
• Materials Science

Background:

• Plasmonic systems, like metal nanoparticles, are crucial in fields from biology to photovoltaics.
• Accurate optical response modeling is vital for designing plasmonic nanomaterials.
• Classical electrodynamics fails for nanoscale systems due to nonlocal and spill-out effects.

Purpose of the Study:

• To review orbital-free (OF) methods derived from linear response Time-Dependent Density Functional Theory (TD-DFT).
• To highlight approximations and properties of OF methods for modeling plasmonic systems.
• To validate OF method accuracy for optical properties of jellium nanoparticles.

Main Methods:

• Derivation of OF methods (semiclassical to Quantum Hydrodynamic Theory) from linear response TD-DFT.
• Validation using jellium nanoparticles as a model plasmonic system.
• Focus on methods scaling linearly with system size for computational efficiency.

Main Results:

• OF methods accurately describe quantum effects in large plasmonic systems.
• These methods provide accurate optical properties without system-specific parameters.
• Accuracy is dependent on the quality of the kinetic energy functional for ground-state electronic density.

Conclusions:

• Orbital-free TD-DFT methods are a powerful, computationally efficient tool for plasmonic systems.
• They offer a viable alternative to computationally expensive full TD-DFT for large-scale applications.
• Future developments should focus on improving universal kinetic energy functionals.