NearDFT

NearDFT refers to approaches that extend density functional theory to account for near-field electromagnetic interactions at the nanoscale. It is used to describe how localized optical fields influence electronic structure and optical responses in systems where the field varies on sub-wavelength scales.

Overview and theory

In standard DFT, electromagnetic fields are often treated in a macroscopic or external manner, while near-field effects require coupling between electronic structure and highly localized fields. nearDFT typically involves incorporating near-field coupling terms into the Kohn–Sham framework, sometimes by solving Maxwell’s equations alongside the electronic problem or by introducing local-field corrections. Various formulations exist, ranging from external near-field potentials to quantum-electrodynamical extensions that integrate light–matter interactions more explicitly. Implementations may be built as extensions to real-space or basis-set DFT codes and can combine DFT with time-dependent or electrodynamics solvers.

Applications

NearDFT is explored for modeling plasmonic and nano-optical phenomena, such as local field enhancements around nanoparticles, excitations in strong localized fields, and charge-transfer processes influenced by near-field gradients. It is also studied in contexts like scanning near-field optical microscopy, nanoantennas, and molecular systems under intense localized illumination.

Status and limitations

NearDFT is an active research area without a universal standard, with multiple competing formulations and code implementations. It is computationally demanding and typically used for specialized investigations rather than routine calculations. Ongoing work focuses on improving accuracy, efficiency, and integration with existing quantum chemistry and electrodynamics tools.

See also

Density functional theory; time-dependent density functional theory; quantum electrodynamics in condensed matter; plasmonics; near-field optics.