Regensburg 2013 – wissenschaftliches Programm
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O: Fachverband Oberflächenphysik
O 28: Focussed Session: Frontiers of Electronic Structure Theory III (jointly with HL and TT)
O 28.3: Vortrag
Dienstag, 12. März 2013, 11:15–11:30, H36
Pressure-induced structural transformations in nanomaterials: a linear-scaling DFT investigation — •Niccolo Corsini1, Peter Haynes1, Carla Molteni2, and Nicholas Hine1 — 1Imperial College, London, UK — 2King's College, London, UK
Semiconductor nanomaterials, including nanocrystals, nanorods and tetrapods, display a number of peculiar and tunable properties that distinguish them from their bulk counterparts and make them versatile materials for use as e.g. effective optical probes in medical diagnostics or photovoltaic devices. Of particular interest is their response to applied pressure, as they transform from one crystalline or amorphous structure to another. Accurate simulations are important for understanding finite size effects in the atomistic mechanisms of phase transformations (difficult to observe clearly in macroscopic experiments), for the opportunity to uncover novel metastable phases stabilized in finite systems, and for potentially innovative applications of nanomaterials. First-principles methods are essential to accurately describe the bond breaking/making in phase transformations and the realistic description of surfaces (often covered by complex surfactants). However the computational cost limits both the length- and time-scales attainable. We have combined an order-N density functional theory code for large systems and an electronic-enthalpy method to apply pressure to finite systems to model with quantum mechanical precision processes induced by pressure in nanomaterials (including their surfaces) under realistic conditions. The focus is on Si, CdSe and CdS nanocrystals that are currently favoured for technological applications.