This contribution is focussed on a set of first-principles molecular dynamics results obtained over the past fifteen years for disordered chalcogenides. In the first part, we sketch and review the historical premises underlying research efforts devoted to the understanding of structural properties in liquid and glassy GexSe1-x systems. We stress the importance of selecting well performing exchange-correlation functionals (within density functional theory) to achieve a correct description of short and intermediate range order. In the second part, we provide a specific, comparative example of structural analysis for chalcogenide GeX4 systems differing by the chemical identity of the X atom. We are able to demonstrate that the correct account of differences between the coordination environments of the two corresponding glasses requires system sizes substantially larger than similar to 100 atoms.

PB - Springer International Publishing CY - Cham VL - 215 SN - 978-3-319-15674-3 UR - http://link.springer.com/10.1007/978-3-319-15675-0 ER - TY - BOOK T1 - Springer Series in Materials ScienceMolecular Dynamics Simulations of Disordered MaterialsMolecular Modeling of Glassy Surfaces Y1 - 2015 A1 - Guido Ori A1 - Carlo Massobrio A1 - Bouzid, A. A1 - Benoit A. Coasne ED - Carlo Massobrio ED - Du, Jincheng ED - Bernasconi, Marco ED - Salmon, Philip S. AB -Progress in computational materials science has allowed the development of realistic models for a wide range of materials including both crystalline and glassy solids. In recent years, with the growing interest in nanoparticles and porous materials, more attention has been devoted to the design of realistic models of glassy surfaces and finely divided materials. The structural disorder in glassy surfaces, however, poses a major challenge which consists of describing such surfaces using computer simulations. In this paper, we show how atomic-scale simulations can be used to develop and investigate the properties of glassy surfaces. We illustrate how both first principles calculations and classical molecular mechanics can be used to follow the trajectory at finite temperature of these systems, and obtain statistical thermodynamic averages to compare against available experiments. Both glassy oxide (silica) and non-oxide (chalcogenide) surfaces are considered.

PB - Springer International Publishing CY - Cham VL - 215 SN - 978-3-319-15674-3 UR - http://link.springer.com/10.1007/978-3-319-15675-0 ER - TY - JOUR T1 - Surface of glassy GeS2: A model based on a first-principles approach JF - Physical Review B Y1 - 2014 A1 - Guido Ori A1 - Carlo Massobrio A1 - Bouzid, A. A1 - Boero, M. A1 - Benoit A. Coasne AB -First-principles calculations within the framework of the density functional theory are used to construct realistic models for the surface of glassy

The structure of glassy GeS2 is studied in the framework of density functional theory, by using a fully self-consistent first-principles molecular dynamics (FPMD) scheme. A comparative analysis is performed with previous molecular dynamics data obtained within the Harris functional (HFMD) total energy approach. The calculated total neutron structure factor exhibits an unprecedented agreement with the experimental counterpart. In particular, the height of the first sharp diffraction peak (FSDP) improves considerably upon the HFMD results. Both the Ge and the S subnetworks are affected by a consistent number of miscoordinations, coexisting with the main tetrahedral structural motif. Glassy GeS2 features a short-range order quite similar to the one found in glassy GeSe2, a notable exception being the larger number of edge-sharing connections. An electronic structure localization analysis, based on the Wannier functions formalism, provides evidence of a more enhanced ionic character in glassy GeS2 when compared to glassy GeS2.

VL - 88 ER -