Elliott, Joshua D.Colonna, NicolaMarsili, MargheritaMarzari, NicolaUmari, Paolo2019-06-282019-06-282019-06-282019-06-0110.1021/acs.jctc.8b01271https://infoscience.epfl.ch/handle/20.500.14299/158622WOS:000471728500023The Bethe Salpeter equation (BSE) can be applied to compute from first-principles optical spectra that include the effects of screened electron hole interactions. As input, BSE calculations require single-particle states, quasiparticle energy levels, and the screened Coulomb interaction, which are typically obtained with many-body perturbation theory, whose cost limits the scope of possible applications. This work tries to address this practical limitation, instead deriving spectral energies from Koopmans-compliant functionals and introducing a new methodology for handling the screened Coulomb interaction. The explicit calculation of the W matrix is bypassed via a direct minimization scheme applied on top of a maximally localized Wannier function basis. We validate and benchmark this approach by computing the low-lying excited states of the molecules in Thiel's set and the optical absorption spectrum of a C-60 fullerene. The results show the same trends as quantum chemical methods and are in excellent agreement with previous simulations carried out at the time-dependent density functional theory or G(0)W(0)-BSE level. Conveniently, the new framework reduces the parameter space controlling the accuracy of the calculation, thereby simplifying the simulation of charge-neutral excitations, offering the potential to expand the applicability of first principles spectroscopies to larger systems of applied interest.Chemistry, PhysicalPhysics, Atomic, Molecular & ChemicalChemistryPhysicsdensity-functional theorywannier functionsexcited-statesenergytext::journal::journal article::research article