Experiments – Simulations – Theories: Multiscale approaches for solutions
1 UMR PECSA, UPMC-Paris 6, CNRS, 4 place Jussieu, 75252 Paris Cedex 05, France
2 ICSM UMR 5257, CEA/CNRS/Université de Montpellier 2/ENSCM, Centre de Marcoule Bât. 426, BP. 17171, 30207 Bagnols sur Cèze Cedex, France
3 Laboratoire Léon Brillouin, UMR CEA-CNRS 12, CEA Saclay, 91191 Gif-sur-Yvette, France
The theory of complex media depends on various levels of description. At the macroscopic scale, hydrodynamic equations are used but they are not valid at small scales, the latter domain can be very important if slow processes occur in the system. At the microscopic scale, molecular dynamics describe the motion of the atoms individually. The two methods which correspond to different levels of description are complementary, but they are not the only ones. Intermediate methods based on continuous solvent model are able to take proper account of the solute dynamics and they can be applied at an intermediate time scale. We present such multi-scale descriptions in the case of solutions. Such an approach is all the more important in the context of of neutron science since neutron scattering experiments are now able to explore a large time domain: they are able to encompass the intermediate time domain for which intermediate methods are unavoidable.
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