Ab initio optical properties of Si(100)

We compute the linear optical properties of different reconstructions of the clean and hydrogenated Si(100) surface within DFT-LDA, using norm-conserving pseudopotentials. The equilibrium atomic geometries of the surfaces, determined from self-consistent total energy calculations within the Car-Parrinello scheme, strongly influence Reflectance Anisotropy Spectra (RAS), showing differences between the p(2x2) and c(4x2)reconstructions. The Differential Reflectivity spectrum for the c(4x2) reconstruction shows a positive peak at energies < 1 eV, in agreement with experimental results.Comment: fig. 2 correcte

Revisiting the Mamlūk empire : political action, relationships of power, entangled networks, and the sultanate of Cairo in late medieval Syro-Egypt

This chapter’s questions the commonly assumed link between political practices of integration and integrity on the one hand – which appear as empirical realities from many sources and studies – and the Syro-Egyptian Sultanate of Cairo (13th-16th centuries) as a dominant, autonomous and imperial historical actor on the other. It problematizes in particular the holistic nature of these assumptions, their merely descriptive value for understanding the region’s history, and the potentially misleading consequences of their normative character. At the same time, this chapter proposes to reflect further on the powerful idea of the Sultanate as an empire. It actually considers this notion of “empire” as a useful way out of this predicament, because it invites to engage with insights from other fields of historical research and to define valuable analytical tools, including from social network theory, to further and refine current assumptions about and understandings of late medieval Syro-Egyptian political action. Confronting such tools with various cases from the center and the peripheries of that Syro-Egyptian political action, this chapter argues that the imperial appearances of the Syro-Egyptian Sultanate were always constructed in the micro-history of people and their negotiation of particular cultural, socio-economic and political relationships, which were extremely fluid and multivalent, permeable, and continuously organized around the court in Cairo