The structure of molecular liquids containing hydrogen : combining neutron diffraction, molecular dynamics and Reverse Monte Carlo
Lundi 9 mai 2016 14:00
- Duree : 1 heure
Lieu : ILL 4, Seminar Room (no 163), 71 avenue des Martyrs - Grenoble
Orateur : László PUSZTAI (Wigner Research Centre for Physics, Hungarian Academy of Sciences - Budapest - Hungary)
The problem of information deficiency, i.e., when the number of available diffraction experiments is (in many cases, much) lower than the number of partial radial distribution functions in the system, is considered. The focus is put on hydrogen-containing molecular liquids, like water, aqueous solutions, alcohols and alcohol-water mixtures. For such liquids, neutron diffraction with H/D isotopic substititution is a natural choice ; here, recent results using polarization analysis on the D3 instrument will be summarized.
Concerning the structural modeling side, two approaches, both relying heavily on Reverse Monte Carlo (RMC) modeling [1] are sketched : (1) molecular dynamics simulation, followed by RMC modeling (‘RMCMD’), and (2) RMC modeling that incorporates the extensive use of interatomic potential functions (‘RMC_POT’). We show that applying either method is useful, although the ‘RMCMD’ scheme appears to be more restricted to smaller molecules (unless the ’RMC_POT’ software, with potentials, is applied for the RMC modeling part). With larger molecules, the molecular structure begins to dominate the measurable total scattering structure factor and therefore, Reverse Monte Carlo is expected to play a more and more important role in conformational analyses in the liquid state (see, e.g., [2]).
References
[1] R.L. McGreevy, L. Pusztai, Molecular Simulation 1, 359 (1988)
[2] O. Gereben, L. Pusztai, J. Comput. Chem. 33, 2285 (2012)
Contact : dubouloz@ill.fr
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