Dresden 2011 – scientific programme
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MM: Fachverband Metall- und Materialphysik
MM 7: Computational Materials Modelling II
MM 7.2: Talk
Monday, March 14, 2011, 14:45–15:00, IFW B
(contribution withdrawn) Dispersion interactions in room-temperature ionic liquids: Results from a non-empirical density functional — •Carlos Pinilla1, Emilio Artacho2, Jose Soler3, Tristan Youngs4, and Jorge Kohanoff4 — 1ICTP, Strada Costiera 11, 34151, Trieste, Italy — 2Dept. Earth Sciences, University of Cambridge, CB2 3EQ, UK — 3Universidad Autonoma de Madrid, Cantoblanco, Spain — 4ASC, Queens University Belfast, BT7 1NN, UK
The role of dispersion interactions in imidazolium-based room-temperature ionic liquids is studied within the DFT framework, using a recently developed non-empirical functional[1], as efficiently implemented in SIESTA[2]. We present results for the equilibrium structure and lattice parameters of several crystalline phases, finding a general improvement with respect to LDA and GGA. In particular, equilibrium volumes reproduce experimental values to unprecedented accuracy. Intra-molecular geometries are retained, while intermolecular distances and orientations are improved relative to LDA and GGA. The quality is superior to that from tailor-made empirical VDW corrections. We provide some insight into the issue of polymorphism of [bmim][Cl] crystals, and present results for the geometry and energetics of [bmim][Tf] and [mmim][Cl] clusters. By comparing to quantum chemical MP2 calculations on clusters, we validate VDW geometries and binding energies. Finally, we also analyze the performance of an optimized version of this functional[3]. [1] M. Dion et al. Phys. Rev. Lett. 92(2004).[2] G. Román-Pérez et al. Phys. Rev. Lett. 103(2009).[3]J. Klimes, D. et al. J. Phys.:Cond. Mat. 22(2010)