Publications

2007

• Time-dependent density functional theory scheme for efficient calculations of dynamic (hyper)polarizabilities
  
  • Andrade X.
  • Botti Silvana
  • A. L. Marques M.
  The Journal of Chemical Physics, American Institute of Physics, 2007, 126, pp.184106. The authors present an efficient perturbative method to obtain both static and dynamic polarizabilities and hyperpolarizabilities of complex electronic systems. This approach is based on the solution of a frequency-dependent Sternheimer equation, within the formalism of time-dependent density functional theory, and allows the calculation of the response both in resonance and out of resonance. Furthermore, the excellent scaling with the number of atoms opens the way to the investigation of response properties of very large molecular systems. To demonstrate the capabilities of this method, they implemented it in a real-space (basis-set-free) code and applied it to benchmark molecules, namely, CO, H2O, and para-nitroaniline. Their results are in agreement with experimental and previous theoretical studies and fully validate their approach. (10.1063/1.2733666)
  DOI : 10.1063/1.2733666
• Optical properties and valence state of Sm ions in aluminoborosilicate glass under β-irradiation
  
  • Malchukova E.
  • Boizot B.
  • Petite G.
  • Ghale D.
  Journal of Non-Crystalline Solids, Elsevier, 2007, 353 (24-25), pp.2397-2402. Sm-doped borosilicate glasses exposed to β-irradiation with doses from 8 × 105 up to 4 × 109 Gy have been studied by luminescence, Raman and electron paramagnetic resonance (EPR) spectroscopies. The luminescence spectra for pristine and irradiated glasses reveal that the β-irradiation process affects valence state of samarium ions. Intense emission at 684 and 727 nm excited by Ar+ laser (514.5 nm) due to the transition of Sm2+ ion was observed after irradiation. Relative proportion of Sm2+ ions estimated as a function of both Sm2O3 content and irradiation dose has the tendency to increase with increasing irradiation dose. In contrast, the EPR spectra of the studied samples reveal a decrease of the defect content, which are mostly hole defects, produced during irradiation, as a function of Sm2O3 content. Finally, the addition of Sm2O3 leads to a decrease of the Si–O–Si bending vibration modes shift and polymerisation changes under irradiation