title: Combining cell-based hydrodynamics with hybrid particle-field simulations: efficient and realistic simulation of structuring dynamics.
abstract: We have extended an existing hybrid MD-SCF simulation technique that employs a coarsening step to enhance the computational efficiency of evaluating non-bonded particle interactions. This technique is conceptually equivalent to the single chain in mean-field (SCMF) method in polymer physics, in the sense that non-bonded interactions are derived from the non-ideal chemical potential in self-consistent field (SCF) theory, after a particle-to-field projection. In contrast to SCMF, however, MD-SCF evolves particle coordinates by the usual Newton's equation of motion. Since collisions are seriously affected by the softening of non-bonded interactions that originates from their evaluation at the coarser continuum level, we have devised a way to reinsert the effect of collisions on the structural evolution. Merging MD-SCF with multi-particle collision dynamics (MPCD), we mimic particle collisions at the level of computational cells and at the same time properly account for the momentum transfer that is important for a realistic system evolution. The resulting hybrid MD-SCF/MPCD method was validated for a particular coarse-grained model of phospholipids in aqueous solution, against reference full-particle simulations and the original MD-SCF model. We additionally implemented and tested an alternative and more isotropic finite difference gradient. Our results show that efficiency is improved by merging MD-SCF with MPCD, as properly accounting for hydrodynamic interactions considerably speeds up the phase separation dynamics, with negligible additional computational costs compared to efficient MD-SCF. This new method enables realistic simulations of large-scale systems that are needed to investigate the applications of self-assembled structures of lipids in nanotechnologies.
authors.affiliation: Leiden Institute of Chemistry, Leiden University, P.O. Box 9502, 2300 RA Leiden, The Netherlands. a.sevink@chem.leidenuniv.nl.
authors.forename: G J A
authors.identifier: http://orcid.org/0000-0001-8005-0697
authors.initials: GJ
authors.lastname: Sevink
authors.affiliation: Institut for Physik, Johannes Gutenberg Univeristat Mainz, Staudingerweg 7-9, 55128 Mainz, Germany.
authors.forename: F
authors.initials: F
authors.lastname: Schmid
authors.affiliation: Department of Physics, Tohoku University, Aoba, Aoba-ku, Sendai 980-8578, Japan.
authors.forename: T
authors.initials: T
authors.lastname: Kawakatsu
authors.affiliation: Dipartimento di Chimica e Biologia, Universit degli Studi di Salerno, via Ponte don Melillo, Fisciano, Italy.
authors.forename: G
authors.initials: G
authors.lastname: Milano
mesh_terms: D057446:Hydrodynamics; D056004:Molecular Dynamics Simulation; D012997:Solvents / Q000737:chemistry
chemical_list: D012997:Solvents