All-electron full-potential implementation of real-time TDDFT in exciting

TL;DR

This paper introduces a highly precise implementation of real-time TDDFT using LAPW+lo basis in the exciting code, enabling detailed simulations of electronic excitations in materials.

Contribution

It presents the first full-potential LAPW+lo implementation of RT-TDDFT in exciting, with benchmarking and application examples demonstrating its accuracy and versatility.

Findings

Good agreement with existing RT-TDDFT and linear-response TDDFT results

Successfully simulated laser-induced excitations in MoS2

Modeled third harmonic generation in silicon and pump-probe in diamond

Abstract

Linearized augmented planewaves combined with local-orbitals (LAPW+lo) are arguably the most precise basis set to represent Kohn-Sham states. When employed within real-time time-dependent density functional theory (RT-TDDFT), they promise ultimate precision achievable for exploring the evolution of electronic excitations. In this work, we present an implementation of RT-TDDFT in the full-potential LAPW+lo code exciting. We benchmark our results against those obtained by linear-response TDDFT with exciting and by RT-TDDFT calculations with the Octopus code, finding a satisfactory level of agreement. To illustrate possible applications of our implementation, we have chosen three examples: the dynamic behavior of excitations in MoS$_2$ induced by a laser pulse, the third harmonic generation in silicon, and a pump-probe experiment in diamond.