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Density-of-states of crystalline 2,2 '-bithiophene: ab initio analysis and comparison with inelastic neutron scattering response
Auteur(s): Hermet P., Bantignies J.-L., Rahmani A., Sauvajol J.-L., Johnson M. R.
(Article) Publié:
Journal Of Physics: Condensed Matter, vol. 16 p.7385-7396 (2004)
Résumé: Phonons in the crystalline phase of 2,2'-bithiophene (2T) are investigated using the direct method combined with density functional theory (DFT)based total energy calculations. Phonon calculations are performed as a function of the long range interactions and the displacement amplitude used for calculating Hellmann-Feynman forces. For the first time, we show that both these parameters are crucial in simulating accurately the experimental low-frequency density-of-states of the 2T crystalline phase, obtained from inelastic neutron scattering experiments. The DFT/direct method approach allows the anharmonicity of phonons to be investigated. The anharmonic behaviour of the low-frequency vibrational modes (below 300 cm(-1)) as the high-frequency - vibrational modes at 685, 800 and 885 cm(-1) of the 2T crystalline phase is clearly demonstrated. Except for these three latter high-frequency modes, a harmonic behaviour is observed for the intramolecular modes. The calculation of the multiphonon contribution predicts the appearance of a broad background in the 600-1500 cm(-1) frequency range, as well as defined features around 950 and 1130 cm(-1), in good agreement with the inelastic neutron scattering data. Finally, low-frequency dispersion curves are given.
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Hydrogen bonding in self organized lamellar hybrid silica 
Auteur(s): Bantignies J.-L., Vellutini L., Sauvajol J.-L., Maurin D., Wong Chi Man M., Dieudonne-George P., Moreau J.J.E.
(Article) Publié:
Journal Of Non-Crystalline Solids, vol. 345-346 p.605-609 (2004)
Texte intégral en Openaccess : 
Ref HAL: hal-00164088_v1
DOI: 10.1016/j.jnoncrysol.2004.08.106
WoS: 000225583200115
Exporter : BibTex | endNote
25 Citations
Résumé: X-ray diffraction (XRD) and Fourier transform infrared spectroscopy (FTIR) investigations have been performed to study the self-assembly properties of lamellar organic–inorganic bridged silsesquioxanes. The organic part consists of an alkylene chain (flexible spacer) between two urea groups. For this study, two samples with different chain length (six and twelve carbon atoms) were synthesized. It is pointed out that the self-assembly properties of the organic component are controlled both by the hydrophobic interactions between alkylene chains and by the hydrogen bonds between urea groups. Infrared results clearly show a direct correlation between the strength of the hydrogen-bond and the crystallinity of the organic–inorganic hybrid materials. Furthermore, the study of the asymmetric stretching CH2 correlated with XRD results indicate that the disorder along the alkylene chain decreases with longer chain length.
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EXAFS study of rubidium-doped single-wall carbon nanotube bundles.
Auteur(s): Bantignies J.-L., Alvarez L., Ducleaux L.
Conference: GDR Européen sur les Nanotubes de carbone. (Batz-sur-mer, FR, 2004-10-10)
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Cours de théorie de l'EXAFS: Ecole de spectroscopie d'absorption des rayons X
Auteur(s): Bantignies J.-L.
Conference: Inconnue (Montpellier, FR, 2004-06-21)
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Dynamique vibrationnelle d'oligomères conjugués modèles : le x-bithiophène.
Auteur(s): Hermet P., Bantignies J.-L., Rahmani A., Sauvajol J.-L.
Conference: Modèles et Simulations en Physique de la Matière Condensée. (Palavas les Flots, France, FR, 2004-04)
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Dynamique vibrationnelle d'oligomères conjugués modèles : le x-bithiophène et le x-quaterthiophène.
Auteur(s): Hermet P., Bantignies J.-L., Rahmani A., Sauvajol J.-L.
Conference: 10èmes Journées Simulation Numérique, Matière Condensée et Désordre. (Jussieu, France, FR, 2004-05)
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Auto-organisation et interactions faibles dans les silices hybrides.
Auteur(s): Bantignies J.-L.
Conference: Colloque Physique de la Matière Condensée (Bordeaux, France, FR, 2004-01-20)
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