| 1. |
- Bast, R., et al.
(författare)
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Role of noncollinear magnetization for the first-order electric-dipole hyperpolarizability at the four-component Kohn-Sham density functional theory level
- 2009
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Ingår i: Journal of Chemical Physics. - : American Institute of Physics (AIP). - 0021-9606 .- 1089-7690. ; 130:2
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Tidskriftsartikel (refereegranskat)abstract
- The quadratic response function has been derived and implemented at the adiabatic four-component Kohn-Sham density functional theory level with inclusion of noncollinear spin magnetization and gradient corrections in the exchange-correlation functional-a work that is an extension of our previous report where magnetization dependencies in the exchange-correlation functional were ignored [J. Henriksson, T. Saue, and P. Norman, J. Chem. Phys. 128, 024105 (2008)]. The electric-field induced second-harmonic generation experiments on CF3 Cl and CF3 Br are addressed by a determination of Β- (-2ω;ω,ω) for a wavelength of 694.3 nm, and the same property is also determined for CF3 I. The relativistic effects on the static hyperpolarizability for the series of molecules amount to 1%, 5%, and 9%, respectively. At the experimental wavelength, the contributions to Β due to the magnetization dependence in the exchange-correlation functional are negligible for CF3 Cl and CF3 Br and small for CF 3 I. The noticeable effect of magnetization in the latter case is attributed to a near two-photon resonance with the excited state 1 E3 (nonrelativistic notation). It is emphasized, however, that the effect of magnetization on Β for CF3 I is negligible both in comparison to the total relativistic correction as well as to the effects of electron correlation. It is concluded that, in calculations of hyperpolarizabilities under nonresonant conditions, the magnetization dependence in the exchange-correlation functional may be ignored. © 2009 American Institute of Physics.
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| 2. |
- Linares, Mathieu, et al.
(författare)
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Effects of π -stacking interactions on the near carbon K -edge x-ray absorption fine structure : A theoretical study of the ethylene pentamer and the phthalocyanine dimer
- 2009
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Ingår i: Journal of Chemical Physics. - : American Institute of Physics (AIP). - 0021-9606 .- 1089-7690. ; 130:10
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Tidskriftsartikel (refereegranskat)abstract
- X-ray absorption spectra have been determined for ethylene and free base phthalocyanine at the carbon K -edge with use of the complex polarization propagator method combined with Kohn-Sham density functional theory and the Coulomb attenuated method B3LYP exchange-correlation functional. Apart from isolated molecules, the study includes π -stacked systems of the phthalocyanine dimer and the ethylene dimer, trimer, tetramer, and pentamer. For ethylene, π -stacking involves a reduction in transition energy of the valence π* -band by some 70 meV and large spectral changes (regarding also shape and intensity) of the Rydberg bands. For phthalocyanine, there are large spectral changes in the entire valence π * -part of the spectrum. © 2009 American Institute of Physics.
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| 3. |
- Johansson, N., et al.
(författare)
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Electronic structure of tris(8-hydroxyquinoline) aluminum thin films in the pristine and reduced states
- 1999
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Ingår i: Journal of Chemical Physics. - : American Institute of Physics (AIP). - 0021-9606 .- 1089-7690. ; 111:5, s. 2157-2163
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Tidskriftsartikel (refereegranskat)abstract
- The electronic structure of tris(8-hydroxyquinoline) aluminum (Alq(3)) has been studied in the pristine molecular solid state as well as upon interaction (doping) with potassium and lithium. We discuss the results of a joint theoretical and experimental investigation, based on a combination of x-ray and ultraviolet photoelectron spectroscopies with quantum-chemical calculations at the density functional theory level. Upon doping, each electron transferred from an alkali metal atom is stored on one of the three ligands of the Alq(3) molecule, resulting in a new spectral feature (peak) in the valence band that evolves uniformly when going from a doping level of one to three metal atoms per Alq(3) molecule. (C) 1999 American Institute of Physics. [S0021-9606(99)50628-4].
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| 4. |
- Crispin, Xavier, et al.
(författare)
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Chemisorption of acrylonitrile on the Cu(100) surface: A local density functional study
- 1999
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Ingår i: Journal of Chemical Physics. - : American Institute of Physics (AIP). - 0021-9606 .- 1089-7690. ; 111:7, s. 3237-3251
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Tidskriftsartikel (refereegranskat)abstract
- The possibility of chemically grafting polyacrylonitrile onto transition metal electrodes via electropolymerization leads to promising applications in the fields of corrosion protection or metal surface functionalization. The initial step of the electrografting mechanism is the adsorption of the acrylonitrile monomer on the metal surface from solution. Here, we investigate theoretically this adsorption process on the copper (100) surface; Density Functional Theory is used in the Local Spin Density approximation to describe the electronic and structural properties of acrylonitrile adsorbed on copper clusters. The chemisorption of acrylonitrile on the copper surface is confirmed experimentally via X-Ray Photoelectron Spectroscopy. The thermodynamic characteristics of the adsorption process are also studied via statistical mechanics. Finally, determining the influence of the copper cluster size on the adsorption of acrylonitrile allows to extrapolate the properties of the acrylonitrile/Cu(100) surface from those of acrylonitrile/copper clusters. (C) 1999 American Institute of Physics. [S0021-9606(99)70231-X].
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| 5. |
- Lou, L, et al.
(författare)
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Electronic structure and kinetics of K on graphite
- 2000
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Ingår i: Journal of Chemical Physics. - : AIP Publishing. - 0021-9606 .- 1089-7690. ; 112:10, s. 4788-4796
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Tidskriftsartikel (refereegranskat)abstract
- The K/graphite adsorption system is studied in a cluster model using ab initio density-functional methods. From the investigation of the potential energy surface a lower bound for the potassium atom binding energy 1.5 eV is obtained, and a surface diffusion barrier of 0.2 eV. To simulate experimentally reported thermal desorption spectra, a two-phase kinetic model is investigated and a desorption energy of 1 eV is found. The thermally activated surface diffusion of K atoms leads to intercalation at defects or steps, which is followed by desorption when further heating the sample. A normal mode analysis yields a K-graphite in-phase and out-of-phase vibrational mode with an energy split of 8 meV, which indicates a relatively strong dynamical coupling between the adsorbed K atom and the graphite substrate. The calculated electron density distribution is verified by an accurate reproduction of the measured dipole moment. From a projected density of state analysis we find a K 4s and an antibonding K 4p resonance located slightly above and 2.6 eV above the Fermi level, respectively. The location of the K 4s resonance, with a lower occupied tail, is consistent with an incomplete charge transfer, and the location of the K 4p resonance is consistent with a proposed hot-electron model to explain recent photodesorption data. The new assignment of the K-induced states near the Fermi level resolves previous apparent discrepancies of the charge state of the dispersed K atom. (C) 2000 American Institute of Physics. [S0021-9606(00)70310-2].
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| 6. |
- Abel, Martin, et al.
(författare)
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Collision-induced absorption at wavelengths near 5 micrometers by dense hydrogen gas
- 2009
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Ingår i: J. Chem. Phys.. - : AIP Publishing. ; 131
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Tidskriftsartikel (refereegranskat)abstract
- Based on a recent ab initio interaction-induced dipole surface of collisionally interacting molecular hydrogen pairs H2–H2, we compute the binary absorption coefficients at wavelengths near 5 micrometers at temperatures of 77.5 and 297 K for comparison with existing laboratory measurements. We observe satisfactory agreement of the measurements with our calculations, thereby concluding an earlier study [Gustafsson et al., J. Chem. Phys. 119, 12264 (2003)], which was based on an ab initio interaction-induced dipole surface that was inadequate for the 5 micrometer band.
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| 7. |
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| 8. |
- Afzelius, Mikael, et al.
(författare)
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Semiclassical calculations of collision line broadening in Raman spectra of N-2 and CO mixtures
- 2004
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Ingår i: Journal of Chemical Physics. - : AIP Publishing. - 0021-9606 .- 1089-7690. ; 120:18, s. 8616-8623
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Tidskriftsartikel (refereegranskat)abstract
- We present a detailed theoretical study of pressure-broadened Raman line shapes in binary mixtures of nitrogen and carbon monoxide. The semiclassical Robert-Bonamy theory was used to calculate self-broadened Q-branch linewidths of N-2 and CO, and Lennard-Jones (LJ) potential energy surface parameters were fixed by comparing our results with extensive experimental linewidth data. For the case of N-2, the ab initio PES8 potential energy surface was investigated, however, the anisotropic repulsive part had to be reduced to ensure a good agreement with experimental linewidths. The agreement between calculations and experiments was remarkably good, both for self-broadened N-2 and CO Q-branch linewidths. Yet, our calculations were not able to predict the experimentally observed difference between Q- and S-branch linewidths of self-broadened N-2. The central results of this work are the Q-branch linewidths of N-2-CO and CO-N-2, which have been calculated through an extrapolation of the parameters of the potential energy surfaces used for self-broadened linewidths by common combination rules. (C) 2004 American Institute of Physics.
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| 9. |
- Agosta, Lorenzo, et al.
(författare)
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Diffusion and reaction pathways of water near fully hydrated TiO2 surfaces from ab initio molecular dynamics
- 2017
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Ingår i: Journal of Chemical Physics. - : AIP Publishing. - 0021-9606 .- 1089-7690. ; 147:2
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Tidskriftsartikel (refereegranskat)abstract
- Ab initio molecular dynamics simulations are reported forwater-embedded TiO2 surfaces to determine the diffusive and reactive behavior at full hydration. A three-domain model is developed for six surfaces [rutile (110), (100), and (001), and anatase (101), (100), and (001)] which describes waters as hard (irreversibly bound to the surface), soft (with reduced mobility but orientation freedom near the surface), or bulk. The model explains previous experimental data and provides a detailed picture of water diffusion near TiO2 surfaces. Water reactivity is analyzed with a graph-theoretic approach that reveals a number of reaction pathways on TiO2 which occur at full hydration, in addition to direct water splitting. Hydronium (H3O+) is identified to be a key intermediate state, which facilitates water dissociation by proton hopping between intact and dissociated waters near the surfaces. These discoveries significantly improve the understanding of nanoscale water dynamics and reactivity at TiO2 interfaces under ambient conditions.
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| 10. |
- Agosta, Lorenzo, et al.
(författare)
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Self-assembly of a triply periodic continuous mesophase with Fddd symmetry in simple one-component liquids
- 2020
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Ingår i: Journal of Chemical Physics. - : AIP Publishing. - 0021-9606 .- 1089-7690. ; 152:19
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Tidskriftsartikel (refereegranskat)abstract
- Triply periodic continuous morphologies (networks) arising as a result of the microphase separation in block copolymer melts have so far never been observed self-assembled in systems of particles with spherically symmetric interaction. We report a molecular dynamics simulation where two simple one-component liquids form upon cooling an equilibrium network with the Fddd space group symmetry. This complexity reduction in the liquid network formation in terms of the particle geometry and the number of components evidences the generic nature of this class of phase transition, suggesting opportunities for producing these structures in a variety of new systems.
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