High throughput selection of organic cathode materials.

Efficient and affordable batteries require the design of novel organic electrode materials to overcome the drawbacks of the traditionally used inorganic materials, and the computational screening of potential candidates is a very efficient way to identify prospective solutions and minimize experimental testing. Here we present a DFT high-throughput computational screening where 86 million molecules contained in the PUBCHEM database have been analyzed and classified according to their estimated electrochemical features. The 5445 top-performing candidates were identified, and among them, 2306 are expected to have a one-electron reduction potential higher than 4 V versus (Li/Li ).

A new protocol for the identification of singlet fission sensitizers through computational screening.

Although singlet fission presents deep advantages or the generation of solar energy, the list of efficient singlet fission sensitizers is still very short, encouraging the theoreticians to focus their efforts on selecting and designing new candidates. Here, it is presented a computational protocol for the efficient screening of databases to select those species matching the energy requirements for singlet fission. Hence, out of the initial 29,123 species, 254 molecules (0.

Improvement of the electrochemical and singlet fission properties of anthraquinones by modification of the diradical character.

In this work, theoretical methods of quantum chemistry are employed to estimate the effects that the structural modification of 1,5- and 9,10-anthraquinone molecules might produce in their electronic structure, in the pursuit of a common strategy to improve the electrochemical and singlet fission features of conjugated quinones. The proposed modifications are the following: (i) substitution of the carbonyl oxygen atom, (ii) insertion of heteroatoms in the carbon backbone, and (iii) introduction of electron-withdrawing and electron-donating substituents in different positions of the rings. This work shows how specific modifications of the electronic structure can be used to tune the electrochemistry and photophysics of the quinones, improving their suitability to be singlet fission sensitizers and cathode materials.

Theoretical design of conjugated diradicaloids as singlet fission sensitizers: quinones and methylene derivatives.

The electronic structures of 206 carbonyls and methylene derivatives based on conjugated cyclic hydrocarbons are computationally studied in this work using theoretical methods of quantum chemistry. The singlet open-shell nature of the ground state and its influence on the low-lying excited states is analyzed for 90 carbonyl (quinone, Q), 90 methylene (quinone dimethide, QDM) and 26 carbonyl-methylene (quinone methide, QM) mixed derivatives in the pursuit of new promising candidates for singlet fission sensitizers. Non-negligible diradical character is observed for most of the studied molecules, which is mainly determined by the nature and the relative position of the substituting groups in the bare rings.

A computational study of the interaction of graphene structures with biomolecular units.

Due to the great interest that biochemical sensors constructed from graphene nanostructures have raised recently, in this work we analyse in detail the electronic factors responsible for the large affinity of biomolecular units for graphene surfaces using ab initio quantum chemical tools based on density functional theory. Both finite and periodic graphene structures have been employed in our study. Whereas the former allows the analysis of the different energy components contributing to the interaction energy separately, the periodic structure provides a more realistic calculation of the total adsorption energy in an extended graphene surface and serves to validate the results obtained using the finite model.

Evaluation of modern DFT functionals and G3n-RAD composite methods in the modelization of organic singlet diradicals.

The evaluation of four high-level composite methods based on the modification of Gaussian-3 (G3) theory for radicals and 18 exchange-correlation density functionals, including modern long-range and dispersion-corrected functionals, in the modelization of singlet diradicals has been performed in this work. Structural parameters and properties such as singlet-triplet gaps, electron affinities, ionization potentials, dipole moments, enthalpies of formation, and bond dissociation energies have been calculated in a set of six well-characterized singlet diradicals, and benchmarked against experimental data and wavefunction-based CASSCF/CASPT2 calculations. The complexity of the open-shell singlet ground state is revealed in the difficulties to properly represent the diradical character reported by some DFT functionals, specially those that do not comprise a certain amount of Hartree-Fock exchange in their formulation.