Berlin 2008 – wissenschaftliches Programm

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HL: Fachverband Halbleiterphysik

HL 36: Poster III

HL 36.1: Poster

Mittwoch, 27. Februar 2008, 16:30–19:00, Poster D

Theory of the low temperature phase of succinonitrile — •Imad Belabbas, Johan Carlsson, and Matthias Scheffler — Fritz-Haber-Institut der Max-Planck Gesellschaft, Faradayweg 4-6, D-14 195 Berlin-Dahlem (Germany)

Recently, succinonitrile has emerged as a promising solid electrolyte for lithium batteries [1]. Succinonitrile is a molecular crystal that crystallizes into two different phases. Below 233 K, succinonitrile has a perfectly ordered structure that only contains gauche isomers. Between, 233 K and 331 K, succinonitrile is a plastic crystal that contains a mixture of molecules with gauche and trans conformations. As a first step toward studying the full properties of succinonitrile, we have investigated the crystal structure of the low temperature phase. For the latter, only the lattice parameters are known, but not the position of the molecules in the unit cell. We have adopted a two steps approach, where force field and density-functional theory (DFT) calculations were applied. Initially, an extended scan of the configurational space was performed where the structures were ordered according to their non-bonded molecular interaction energy. This provided a set of potential candidates that were used as input for a global minimum energy search procedure based on genetic algorithms. The obtained configuration of the unit cell was further refined by means of DFT calculations. This procedure led to a theoretical structural model for the low temperature phase of succinonitrile.

[1]- J. P. Alarco, Y. Abu-Lebdeh, A. Abouimrane and M. Armand, Nature Materials, 3, 476 (2004).