Time-dependent density-functional theory for electronic excitations in materials: basics and perspectives

TL;DR

This paper explains the fundamentals of time-dependent density-functional theory (TDDFT) for electronic excitations, discusses recent advances, and highlights challenges in applying TDDFT to materials and nanostructures.

Contribution

It provides a pedagogical overview of TDDFT formalism and discusses recent developments and challenges in extending TDDFT to complex materials and nanostructures.

Findings

Explains TDDFT formalism using a two-level system

Highlights recent advances in TDDFT for materials

Discusses challenges like excitonic effects and plasmon excitations

Abstract

Time-dependent density-functional theory (TDDFT) is widely used to describe electronic excitations in complex finite systems with large numbers of atoms, such as biomolecules and nanocrystals. The first part of this paper will give a simple and pedagogical explanation, using a two-level system, which shows how the basic TDDFT formalism for excitation energies works. There is currently an intense effort underway to develop TDDFT methodologies for the charge and spin dynamics in extended systems, to calculate optical properties of bulk and nanostructured materials, and to study transport through molecular junctions. The second part of this paper highlights some challenges and recent advances of TDDFT in these areas. Two examples are discussed: excitonic effects in insulators and intersubband plasmon excitations in doped semiconductor quantum wells.