1000 resultados para First hyperpolarizability
Resumo:
EXAFS has been used to directly show the existence of Au…Au interactions in dissolved Au(I) complexes for the first time; the information has been used to understand the optical properties of these materials.
Resumo:
There is growing concern within the profession of pharmacy regarding the numerical competency of students completing their undergraduate studies. In this 7 year study, the numerical competency of first year pharmacy undergraduate students at the School of Pharmacy, Queen's University Belfast, was assessed both on entry to the MPharm degree and after completion of a basic numeracy course during the first semester of Level 1. The results suggest that students are not retaining fundamental numeracy concepts initially taught at secondary level education, and that the level of ability has significantly decreased over the past 7 years. Keywords: Numeracy; calculations; MPharm; assessment
Resumo:
(1x1) and (2x1) reconstructions of the (001) SrTiO3 surface were studied using the first-principles full-potential linear muffin-tin orbital method. Surface energies were calculated as a function of TiO2 chemical potential, oxygen partial pressure and temperature. The (1x1) unreconstructed surfaces were found to be energetically stable for many of the conditions considered. Under conditions of very low oxygen partial pressure the (2x1) Ti2O3 reconstruction [Martin R. Castell, Surf. Sci. 505, 1 (2002)] is stable. The question as to why STM images of the (1x1) surfaces have not been obtained was addressed by calculating charge densities for each surface. These suggest that the (2x1) reconstructions would be easier to image than the (1x1) surfaces. The possibility that the presence of oxygen vacancies would destabilise the (1x1) surfaces was also investigated. If the (1x1) surfaces are unstable then there exists the further possibility that the (2x1) DL-TiO2 reconstruction [Natasha Erdman Nature (London) 419, 55 (2002)] is stable in a TiO2-rich environment and for p(O2)>10(-18) atm.