Welcome to the tutorial for Real-Time Time-Dependent DFT (RT-TDDFT) in FHI-aims!

Prepared by Christopher Shepard

This is a tutorial for using real-time time-dependent DFT (RT-TDDFT) in FHI-aims to study non-equilibrium dynamics of electrons in various systems. Possible applications include absorption spectrum calculations based on the dynamical dipole response, high-harmonic generation simulations or ion bombardment simulations based on non-adiabatically coupled electron-ion dynamics (Ehrenfest dynamics). In this tutorial we focus on some simple examples which highlight the utility of RT-TDDFT.

Input files are available within this repo, in each specific Tutorial directory. In this tutorial we the basic theory behind RT-TDDFT (Tutorial-1), calculating the absorption spectra of isolated molecules (Tutorial-2) and periodic systems (Tutorial-3), and Ehrenfest dynamics (Tutorial-4).

All files, including inputs and solutions, can be found here

A current copy of the FHI-aims manual can be found here

Prerequisites

Users of this tutorial should have:

• a sufficiently good understanding of the Unix command line,
• an installed FHI-aims executable (cf. preparations),
• access to a sufficiently powerful computer. For this tutorial a laptop with at least two (physical cores) should be sufficient,
• an understanding on basics of Running FHI-aims.

Summary of Tutorial

The tutorial is organised as follows:

Part 1 covers the basic theory behind RT-TDDFT.

Part 2 simulates the absoprtion spectra of an isolated water molecule using RT-TDDFT.

Part 3 simulates the absoprtion spectra of crystalline silicon using RT-TDDFT.

Part 4 denonstrates how to run RT-TDDFT with Ehrenfest dynamics.