What is it about?

The effect of cross-linking Se chains by Ge atoms in the system GeSe9 was investigated by combining neutron diffraction with first principles molecular dynamics (FPMD). We investigated the impact of three key variables in simulating the structure of glasses by FPMD, namely (i) the system size, (ii) the quench schedule, and (iii) the final relaxation time at room temperature.

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Why is it important?

The GeSe9 system proved to be particularly challenging for FPMD simulations because of the small concentration of Ge atoms and the small system size. A sizeable proportion of this small number of Ge atoms was trapped in unrepresentative configurations in the liquid, which had little chance to evolve during the time scale of the simulation. The work highlights the crucial roles played both by the quench schedule prior to relaxation at room temperature and by the relaxation process itself. It thereby outlines some of the pitfalls for the unwary.

Perspectives

The Ge-Se system has provided a test-bed for the development of first principles molecular dynamics techniques for disordered chalcogenide materials, aided by the structural information gained from neutron diffraction experiments.

Professor Philip S Salmon
University of Bath

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This page is a summary of: Structure of amorphous GeSe9 by neutron diffraction and first-principles molecular dynamics: Impact of trajectory sampling and size effects, The Journal of Chemical Physics, August 2016, American Institute of Physics, DOI: 10.1063/1.4961265.
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