Can We See the Energy Densities? I. Insights from Real-Time Time-Dependent Density Functional Theory Simulations

In this work, we report a scheme to evaluate and analysis of energy density fluctuations during the real-time time-dependent density functional theory (RT-TDDFT) simulations. Using Ag₄–N₂ complexes as examples, it is shown that the energy of each molecular fragment (such as Ag₄ and N₂) can be readily computed by partitioning Kohn-Sham energy densities using Becke or fragment-based Hirshfeld (FBH) scheme. A strong orientation-dependence is observed for theenergy flow between the Ag₄ cluster and a nearby N₂ molecule in the RT-TDDFT simulations. Future applications of such an energy density analysis in electron dynamics simulations are
discussed.