Non-empirical double-hybrid density functionals as reliable tools for electronic structure calculations

The development of universal and accurate approximations for electronic structure calculations lies at the central core of (past and modern) research in theoretical and computational chemistry. For that purpose, any reliable method needs to treat in a balanced way exchange and correlation effects arising from the intricate structure of matter at the nanoscopic level. Following this principle, we have developed a set of non-empirical (double-hybrid) density functional expressions, minimizing the parameterization and also widely applicable even for systems of considerable size, while being accurate enough to compete with wavefunction methods or even matching experimental information. The underlying expressions are now implemented in many available codes worldwide, then allowing the access to the whole set of key properties needed for addressing chemical structure, reactivity, and bonding, at all nanostructured levels and/or states of matter. Additionally, the recent extension to excited states through a time-dependent (linear-response) formalism also allows one to deal with photochemistry, photophysical, and related properties. Therefore, this family of methods can now be successfully applied to organic, inorganic, or biomolecular compounds, or any other complex system, within an affordable computational effort.