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Accueil > Séminaires > 2014

Vibrational spectroscopy with DFTB-MD in the gas phase : is it accurate enough in comparison to DFT-MD ?

Marie-Laure Bonnet, Université d’Evry

Séminaire LCPQ

Salle de séminaire IRSAMC

Study the behaviour of the interactions at the solid/liquid interface is an important ecological goal in order to a better understanding soil pollution such as soil erosion, sub-soil contamination by biological molecules. In order to study it, we need to consider molecular systems with more than thousands of atoms. For this reasons, BOMD (Born-Oppenheimer Molecular Dynamics) is not reasonable.

With BOMD, the simulation of few nanosecond will ask some months, in contrary with DFTB-MD (DFT-Tight binding Molecular Dynamics) [1] which is a semi-empirical methods based on DFT, will be done in few days to few weeks but parameters are needed.

Before to carry out such calculation, this method needs to be benchmarked. DFTB-MD was performed on small neutral and protonated peptides and compare to previous works with BOMD associated to vibrational spectroscopy [2]. A particularly emphasis is given on DFTB-MD on charged peptides, as this method is known to have some problems to describe correctly charged organic molecules.

References.

[1] (a) W.M.C. Foulkes, et al., Phys. Rev. B, 1989 ; (b) D. Porezag, et al., Phys. Rev. B, 1995 ; (c) G. Seifert, et al., Int. J. Quantum Chem., 1996 ; (d) M. Elstner, et al., Phys. Rev. B, 1998.

[2] (a) M.-P. Gaigeot, et al., J. Chem. Theory Comput. 2005. (b) D. C. Marinica, et al., J. Phys. Chem. A, 2006 ; (c) C. Cimas, et al., J. Chem. Theory Comput. 2009.