Modeling Electromagnetic Phenomena in Large Quantum Systems

Ore: 14.00
Luogo: videoconferenza tramite Zoom (il link di accesso può essere richiesto a df.supportstaff [at] unitn.it)

Speaker

• Amir Boag, Tel Aviv University

Abstract

Density Functional Theory (DFT) is a common method for quantum calculations that offers a good balance between accuracy and computational cost. An important challenge in both ground state and excited state DFT is the calculation of electrostatic and electrodynamic induced potentials, as well as the Fock exchange interaction. For the ground state, we present an accurate scalar Green’s function kernels to efficiently evaluate the Hartree and Fock potentials using a Fast Fourier Transform (FFT) method to solve the Poisson equation. We demonstrate the efficiency of this method, using hybrid and screened hybrid DFT, to study the properties of silicon quantum dots comprising over a thousand atoms (3nm diameter). In the excited state, electrodynamic fields are formally incorporated within time dependent Density Functional Theory (TDDFT) by considering both induced scalar and vector potentials. The Hamiltonian is described in both the Coulomb and Lorenz gauges, and the advantages of the latter are outlined. Integral expressions are defined for the retarded potentials of each gauge and a methodological approach to evaluating these nontrivial expressions with a low computational cost is adopted. The faster potential calculations enables the study of larger systems, such as nanoscale antennas.