1,721,132 research outputs found
Multi-scale integrated computational approaches: applications in material and life sciences
No full textAb initio modeling of complex chemical systems
No full textReview su invito. Questa pubblicazione offre una panoramica delle attuali metodologie in modellistica computazionale: gli approcci teorici allo stato dell’arte sono discussi in relazione alla loro accuratezza e al relativo costo computazionale, mettendone in luce alcune applicazioni di successo e i limiti
Theoretical modelling of weakly bound molecular complexes in the ground and excited electronic states: semi-empirical DFT versus post-HF approaches
No full textFrom oxide to proton conduction: A quantum-chemical perspective on the versatility of Sr2Fe1.5Mo0.5O6−δ-based materials
No full textSr2Fe1.5Mo0.5O6-delta (SFMO) is a promising electrode material for solid oxide electrochemical cells. This perspective highlights the role of first-principles investigations in unveiling SFMO structural, electronic, and defect properties. In particular, DFT+U provides a reliable and convenient tool for extensive studies on strongly correlated transition-metal oxides, as SFMO and related systems. The SFMO excellent performances are ascribed to a mixed oxide ion-electron conductor character. Crucial features are the easy formation of oxygen vacancies and the low oxide migration barrier heights. Aliovalent doping with K+ enables convenient hydration and effective proton transport in bulk SFMO. This opens a route toward new promising triple-conductor oxides. Besides discussion of specific SFMO applications, our results help to uncover general perovskite-oxide features and new design principles for oxide- and proton-conducting solid oxide fuel cell electrodes
Structure and energy level alignment at the dye-electrode interface in p-type DSSCs: new hints on the role of anchoring modes from ab initio calculations
No full textp-type dye-sensitized solar cells (DSSCs) represent the complementary photocathodes to the well-studied n-type DSSCs (Grätzel cells), but their low performances have hindered the development of convenient tandem solar cells based on cost-effective n- and p-type DSSCs. Because of their low efficiencies, experimental investigations highlighted the role of hole-electron transport processes at the dye-electrode interface. However, the effects of the dye anchoring groups on interfacial electronic features are still unclear. We report here a first principles study of a benchmark p-type DSSC model, namely the widely used Coumarin-based dye C343 adsorbed on the p-NiO surface. Together with the original carboxylic acid, we test the alternative phosphonic acid as the anchoring group. We investigate binding energies, structural features and electronic energy level alignments: our results highlight that these properties are highly sensitive to the binding modes. In particular, both the chemical nature of the anchoring group and the binding mode strongly affect the thermodynamic driving force for the dye-electrode hole injection process. From analysis of the electronic densities, we find that favorable driving forces are correlated with small values of the interfacial electrostatic dipole that is formed upon dye adsorption. From our results, we derive new hints for improving open circuit potential and the hole injection process in p-type DSSCs based on NiO electrodes
Toward an effective modelling of weakly bound molecular complexes: modified DFT-D scheme for stacking/dispersion and hydrogen bond interactions
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