Electronic circular dichroism with real time time dependent density functional theory: Propagator formalism and gauge dependence

Abstract

Linear response theory is reviewed in a propagator formalism to treat linear response and real time (RT) time dependent density functional theory (TDDFT) in a common framework for the calculation of linear response tensors. The importance of an additional term in the definition of the momentum for a description in the velocity representation as well as an origin independent linear magnetic response in the presence of non-local pseudo potentials is discussed. The origin and meaning of the terms ‘representation’ and ‘gauge’ are explored and simulations of absorption and electronic circular dichroism spectra using RT-TDDFT are presented. The calculation of the electro-magnetic linear response functions has been implemented into the package CP2K using the gaussian and (augmented) plane wave method.