Structure of a Model Dye/Titania Interface: Geometry of Benzoate on Rutile-TiO2 (110)(1 x 1)

Scanned-energy mode photoelectron diffraction (PhD) and ab initio density functional theory calculations have been employed to investigate the adsorption geometry of benzoate ([C6H5COO]−) on rutile-TiO2(110)(1 × 1). PhD data indicate that the benzoate moiety binds to the surface through both of its oxygen atoms to two adjacent fivefold surface titanium atoms in an essentially upright geometry. Moreover, its phenyl (C6H5−) and carboxylate ([−COO]−) groups are determined to be coplanar, being aligned along the [001] azimuth. This experimental result is consistent with the benzoate geometry emerging from DFT calculations conducted for laterally rather well-separated adsorbates. At shorter interadsorbate distances, the theoretical modeling predicts a more tilted and twisted adsorption geometry, where the phenyl and carboxylate groups are no longer coplanar; i.e., interadsorbate interactions influence the configuration of adsorbed benzoate

Structure of a model dye/titania interface: Geometry of benzoate on rutile-TiO₂(110)(1×1)

Scanned-energy mode photoelectron diffraction (PhD) and ab initio density functional theory calculations have been employed to investigate the adsorption geometry of benzoate ([C₆H₅COO]⁻) on rutile-TiO₂(110)­(1 × 1). PhD data indicate that the benzoate moiety binds to the surface through both of its oxygen atoms to two adjacent fivefold surface titanium atoms in an essentially upright geometry. Moreover, its phenyl (C₆H₅−) and carboxylate ([−COO]⁻) groups are determined to be coplanar, being aligned along the [001] azimuth. This experimental result is consistent with the benzoate geometry emerging from DFT calculations conducted for laterally rather well-separated adsorbates. At shorter interadsorbate distances, the theoretical modeling predicts a more tilted and twisted adsorption geometry, where the phenyl and carboxylate groups are no longer coplanar; i.e., interadsorbate interactions influence the configuration of adsorbed benzoate

Phase stabilities and vibrational analysis of hydrogenated diamondized bilayer graphenes: A first principles investigation

The phase stabilities as well as some intrinsic properties of hydrogenated diamondized bilayer graphenes, 2-dimensional materials adopting the crystal structure of diamond and of lonsdaleite, are investigated using a first-principles approach. Our simulations demonstrate that hydrogenated diamondized bilayer graphenes are thermodynamically stable with respect to bilayer graphene and hydrogen molecule even at 0 GPa, and additionally they are found to withstand the physical change in structure up to at least 1000 K, ensuring their dynamical and thermal stabilities. The studied hydrogenated diamondized bilayer graphenes are predicted not only to behave as direct and wide band gap semiconductors, but also to have a remarkably high resistance to in-plane plastic deformation induced by indentation as implied by their high in-plane elastic constants comparable to those of diamond and of lonsdaleite. The mechanical stability of the materials is confirmed though the fulfilment of the Born stability criteria. Detailed analysis of phonon vibrational frequencies of hydrogenated diamondized bilayer graphenes reveals possible Raman active and IR active modes, which are found to be distinctly different from those of hydrogenated diamond-like amorphous carbon and defective graphene and thus could be used as a fingerprint for future experimental characterization of the materials. © 2019 Elsevier Lt

Geometric structure of TiO2(110)(1X1): confirming experimental conclusions

Low-energy electron-diffraction and surface x-ray diffraction data acquired from TiO2(110)(1X1) are re-analyzed to confirm the integrity of the previously reported optimized geometries. This work is performed in response to ab initio density-functional theory calculations that suggest that the atomic displacements determined from low-energy electron-diffraction measurements may be compromised by the limited number of optimized atom positions. Performing structural optimizations as a function of depth into the selvedge, this present study validates the previous experimental structure determinations

Assessing the Performance of Dispersionless and Dispersion-accounting Methods: Helium Interaction with Cluster Models of the TiO2(110) Surface

18 pags.; 9 figs.; 4 tabs.As a prototypical dispersion-dominated physisorption problem, we analyze here the performance of dispersionless and dispersion-accounting methodologies on the helium interaction with cluster models of the TiO2(110) surface. A special focus has been given to the dispersionless density functional dlDF and the dlDF+Das construction for the total interaction energy (K. Pernal, R. Podeswa, K. Patkowski, and K. Szalewicz, Phys. Rev. Lett. 109 (2009) 263201), where Das is an effective inter-atomic pairwise functional form for the dispersion. Likewise, the performance of Symmetry-Adapted Perturbation Theory (SAPT) method is evaluated, where the interacting monomers are described by density functional theory (DFT) with the dlDF, PBE, and PBE0 functionals. Our benchmarks include CCSD(T)-F12b calculations and comparative analysis on the nuclear bound states supported by the He-cluster potentials. Moreover, intra- and inter-monomer correlation contributions to the physisorption interactionare analyzed through the method of increments (H. Stoll, J. Chem. Phys. 97 (1992) 8449) at CCSD(T) level of theory. This method is further applied in conjunction with a partitioning of the Hartree-Fock interaction energy to estimate individual interaction energy components, comparing them with those obtained using the different SAPT(DFT) approaches. The cluster size evolution of dispersionless and dispersion-accounting energy components is then discussed, revealing the reduced role of the dispersionless interaction and intra-monomer correlation when the extended nature of the surface is better accounted for. On the contrary, both post-Hartree-Fock and SAPT(DFT) results clearly demonstrate the high transferability character of the effective pairwise dispersion interaction whatever the cluster model is. Our contribution also illustrates how the method of increments can be used as a valuable tool not only to achieve the accuracy of CCSD(T) calculations using large cluster models, but also to evaluate the performance of SAPT(DFT) methods for the physically well-defined contributions to the total interaction energy. Overall, our work indicates the excellent performance of a dlDF+Das approach in which the parameters of the dispersion function are optimized using the smallest cluster model of the target surface. It also paves the way for further assessments of the dlDF+Das approach including periodic boundary conditions as a cost-efficient and accurate method to treat van der Waals adsorbate-surface interactions. © 2014 American Chemical SocietyThis work has been performed under Grants Nos. CCG08-CSIC/ESP-3680 from CSIC-CM and FIS2011-29596- C02-01 from DGI, Spain (FEDER). The support of COST Action CM1002 (CoDECS) is also gratefully acknowledged.Peer Reviewe