What does it take to run orbital-free (TD)DFT and embedding simulations? And what do we get from them?*

This talk discusses orbital-free DFT and DFT embedding methods. Both rely on pure density functionals for the noninteracting kinetic energy, exchange and correlation. When venturing to nonequilibrium processes, semiquantitative to quantitative agreement with reality can only be achieved if nonadiabaticity and nonlocality is accounted for. Upon inclusion of nonlocality, embedding simulations reach a sub-kcal/mol accuracy in the inter-subsystem interactions dramatically widening the applicability of DFT to large system sizes. When nonadiabaticity is included in the Pauli potential, orbital-free TDDFT can be used to compute optical spectra and electron dynamics of metal and semiconductor systems with confidence in the usefulness of the results. The talk also touches upon best practices to realize efficient computer software encoding DFT embedding and orbital-free (TD)DFT and how to train the next generation of DFT software developers.