As a result of the work a new Generalised Landau-Lifshitz Fluctuating Hydrodynamics (GLL-FH) equations were derived and implemented into open source MD code Gromacs. Modified version of Gromacs software is published on GitHub (
https://github.com/ikorotkin/gromacs_fhmd(odnośnik otworzy się w nowym oknie)). The new two-way coupling model was tested for preserving correct RDF, VACF functions, standard deviations, on stationary problems such as shear (Couette) flow and non-stationary acoustic wave propagation problem.
One of the most useful improvement of the new model in comparison with the previous one-way coupling method is that the pure FH region (without particles) was implemented into the hybrid model. This means the pure FH approach is now smoothly coupled with the hybrid and pure atomistic approaches closing the multiscale model. Thanks to this, an order of magnitude reduction in computational cost has been achieved in comparison with the all-atom molecular dynamics solution in several numerical test examples of liquid argon simulations in Gromacs.
The theory of GLL-FH, computational scheme, and some numerical examples are described in (Korotkin, I., & Karabasov, S. (2018). A Generalised Landau-Lifshitz Fluctuating Hydrodynamics model for concurrent simulations of liquids at atomistic and continuum resolution.
https://doi.org/10.13140/RG.2.2.19830.45123(odnośnik otworzy się w nowym oknie)).
Another journal article where a new extension of the hybrid MD-FH method to include the shear flow boundary condition induced by the moving boundary is in preparation (authors: J. Hu, I. Korotkin, S. Karabasov). In this paper we apply the new MD-FH method to analyse the self-diffussion property of water and the molecular diffusion of a small peptide in water under shear flow conditions.
Another paper entitled “A multi-resolution particle/fluctuating hydrodynamics model for hybrid simulations of liquids based on the two-phase flow analogy” (Hu, Korotkin, & Karabasov, 2018) has been accepted in the Journal of Chemical Physics.
There are also two journal articles in preparation (authors: F. Li, I. Korotkin, and S. Karabasov). In the first one we analyse the material properties of nano-confined water between graphene sheets under shear flow conditions. In the second article we develop the first all-atom model of an AFM tip moving in a drop of water near the mica substrate including realistic surface interaction effects. The final part of the model with taking into account a large volume of the surrounding water molecules will be developed using the new hybrid MD/FH model, which work is underway.
In addition to the AFM tip simulation, MD simulations of the experiment with artificial ELP-IK24 protein and Graphene Oxide sheets were performed to complement a set of state-of-the-art experiments carried out by Prof. Alvaro Mata and his research group in Queen Mary University. A joint paper about the experiment and its simulation was prepared and submitted to Nature Chemistry journal.
