Description of the interaction of light and matter using the time-dependent density functional theory

In this talk, I present our recent work on the interaction of light and

matter using the Time-Dependent Density Functional Theory (TDDFT). Two

different versions of the TDDFT calculations will be presented. The

first is the orbital-free TDDFT (OF-TDDFT) which can be used in systems with tens

of thousands of atoms. The OF-TDDFT is coupled to the Maxwell-equations

and the electron density and the electric fields are time propagated

to simulate the interaction of light and matter. We have also worked

on extending the TDDFT to describe the interaction of light and

molecules in cavities using a Quantum Electrodynamic (QED) Hamiltonian.

The QED-TDDFT equations are solved by time propagating the wave function

on a tensor product of a Fock-space

and real-space grid. Applications for molecules in cavities show the

accuracy of the approach. Examples include the coupling strength and

light frequency dependence of the energies, wave functions, optical

absorption spectra, and Rabi splitting magnitudes in cavities, as well

as a description of high harmonic generation in cavities.