A generalized operational formula based on total electronic densities to obtain 3D pictures of the dual descriptor to reveal nucleophilic and electrophilic sites accurately on closed-shell molecules

Indexación: Wiley Online Library. Online Version of Record published before inclusion in an issue http://onlinelibrary.wiley.com/doi/10.1002/jcc.24453/fullBy means of the conceptual density functional theory, the so-called dual descriptor (DD) has been adapted to be used in any closed-shell molecule that presents degeneracy in its frontier molecular orbitals. The latter is of paramount importance because a correct description of local reactivity will allow to predict the most favorable sites on a molecule to undergo nucleophilic or electrophilic attacks; on the contrary, an incomplete description of local reactivity might have serio us consequences, particularly for those experimental chemists that have the need of getting an insight about reactivity of chemical reagents before using them in synthesis to obtain a new compound. In the present work, the old approach based only on electronic densities of frontier molecular orbitals is replaced by the most accurate procedure that implies the use of total electronic densities thus keeping consistency with the essential principle of the DFT in which the electronic density is the fundamental variable and not the molecular orbitals. As a result of the present work, the DD will be able to properly describe local reactivities only in terms of total electronic densities. To test the proposed operational formula, 12 very common molecules were selected as the original definition of the DD was not able to describe their local reactivities properly. The ethylene molecule was additionally used to test the capability of the proposed operational formula to reveal a correct local reactivity even in absence of degeneracy in frontier molecular orbitals.http://onlinelibrary.wiley.com/doi/10.1002/jcc.24453/ful

Spin-orbit proximity effect in graphene on metallic substrates: decoration vs intercalation with metal adatoms

The so-called spin-orbit proximity effect experimentally realized in graphene (G) on several different heavy metal surfaces opens a new perspective to engineer the spin-orbit coupling (SOC) for new generation spintronics devices. Here, via large-scale density functional theory (DFT) calculations performed for two distinct graphene/metal models, G/Pt(111) and G/Au/Ni(111), we show that the spin-orbit splitting of the Dirac cones (DCs) in these stuctures might be enhanced by either adsorption of adatoms on top of graphene (decoration) or between the graphene and the metal (intercalation). While the decoration by inducing strong graphene-adatom interaction suppresses the linearity of the G's $\pi$ bands, the intercalated structures reveal a weaker adatom-mediated graphene/substrate hybridization which preserves well-defined although broadened DCs. Remarkably, the intercalated G/Pt(111) structure exhibits splittings considerably larger than the defect-free case