Coarse-graining multicomponent soft matter systems: equilibrium and dynamics
Johannes Gutenberg University, Mainz, Germany
Please expect some delays when traveling via train to Mainz (use S8 or RB75). Updated information (in German) is available here.
Please make your hotel reservation now, the block of reserved rooms will be released on July 10, 2013
1) Abstract submission: please submit your abstract via the CECAM web page by May, 31, 2013.
2) Location of the venue: Max Planck Institute, Ackermannweg 10, 55128 Mainz
The nearest airport is Frankfurt International Airport (FRA). Here you will find directions to the MPI for Polymer Research.
3) Accommodation: A limited number of rooms have been reserved in the HOTEL KÖNIGSHOF.
55116 Mainz, Germany
Phone: + 49 (0)6131- 960 -110
Fax: + 49 (0)6131 – 611 271
Single room: 63.00 euros including breakfast
Double room: 72.00 euros including breakfast
How to get there:
From the main train station in Mainz, cross the street and you should already see the HOTEL KÖNIGSHOF sign written in large yellow letters on the front of the building. For further details, please go to the hotel web page.
RESERVE your room only via e-mail or fax, other means of booking will not be accepted. To get the special Hotel Rate use the following code when making your reservation: CECAM Workshop
4) Reimbursement information: Invited speakers are reimbursed for travel expenses and accommodation up to the limit specified in the invitation email. Please keep all original receipts and use the following form.
Description: Despite seminal advances in the development of computer simulation tools, many phenomena in multicomponent soft-matter and biological systems remain intractable to the present techniques. Specifically, due to the multicomponent nature and the concomitant phase separation or self-assembly, such soft-matter systems often exhibit many metastable states and small free-energy differences between morphologies, which lead to the formation of many defects and non-equilibrium morphologies in experiments. To develop computational frameworks to predictively characterize the structure and properties of such materials, requires not only appropriate equilibrium coarse-graining tools, but also strategies to map the dynamics of relevant “microscopic” degrees of freedom to “macroscopic” variables. In short, techniques emphasizing consistent and simultaneous coarse-graining of both equilibrium and non-equilbrium aspects of soft matter and biological systems are lacking. We expect, however, that recent developments of coarse-graining techniques will result in substantial progress in the near future.
For a lengthy period of development, quantitative computer simulation techniques for soft-matter systems have progressed by focusing on a single “scale” of characterization of phenomena. For instance, when chemical reactions such as proton hopping were modeled, it was customary to study them through quantum mechanical simulations focusing on one or a few atoms. In contrast, when issues such as structure or solvation of fluids were studied, empirical potential-energy force fields based on the molecular positions and orientations of the atoms or the molecules were employed. When larger scale phenomena were considered, molecular granularity is disregarded and the solvent became a continuum characterized by certain thermodynamic and dynamical properties. In a nutshell, depending on the property desired, it was common to use computer simulations centered on electrons (quantum)/molecules (molecular simulations)/continuum to address the phenomena of interest.
Over the past two decades however, there has been an explosion of interest in going beyond the above “compartmentalized approach” and instead link the different scales of simulations and combining particle-based simulations with alternative techniques (e.g., particle-based simulations + Lattice-Boltzmann solvent1 or dynamic self-consistent field approaches2). The main driving force for such efforts have been the increasing emphasis on being able to relate the parameters, which accompany the coarse-grained simulations to the more fine-scale descriptions of matter. In such a manner, the hope is to be able to develop a truly “first-principles” description of the materials and its properties without having the need to perform quantum mechanical simulations on systems of continuum scale!
As a first step, a number of researchers (and CECAM workshops included) have devoted themselves to the above objective as it pertains to equilibrium properties and phenomena.3-5 The latter includes properties such as equation of state for materials, the structure of polymeric and colloidal materials etc. A number of coarse-graining approaches have been proposed to the link the microscopic to macroscopic (and in some cases, reverse mapping) parameters and interactions. Based on such techniques, there have been successful demonstrations of predictions of macroscopic properties and phenomena starting from a microscopic description of matter.
While the above developments have led to considerable insights (albeit, a number of issues still remain in such a context), comparable developments and ideas for nonequilibrium phenomena and dynamics of soft-matter and multicomponent systems are still lacking. Unfortunately, in many such systems, due to multiple degrees of freedom and the accompanying complex free energy landscapes, characteristics such as trapping in nonequilibrium metastable states, defective structures etc. are very common and render the “equilibrium” characteristics less relevant to experiments. A classical and deceptively simple example of such issues is the problem of phase separation in multi-component polymer blends with the addition of a compatibilizer or an evaporating solvent. These systems are ubiquitous in industrial applications, but even the development of accurate (equilibrium) coarse-grained potentials does not suffice to predict the final large-scale morphology of the material, which depends on the processing condition.
We note that while the formal framework of nonequilibrium coarse-graining, known as projection operator techniques, has been known for some time.6, 7 Qualitatively, the degrees of freedom that have been integrated out, contribute to friction and noise in the coarse-grained description.8-10 An implementation of such ideas and related frameworks to computer simulation techniques has not been pursued. However, with the advance of the enhanced computational power arising from the Graphic Processing Units, and the understanding gained through the equilibrium coarse-graining techniques, the time is ripe to bring senior researchers working at the forefront of computational techniques and address some of the unresolved issues in the context of coarse-graining the dynamics of multicomponent soft-matter and biological systems:
• How to rigorously map the dynamics, which includes both the appropriate evolution equation as well as the parameters therein, to microscopic descriptions and the parameters?
• How do degrees of freedom that have been integrated out contribute to friction/noise?
• Is it possible to construct rigorous dynamical evolutions at the coarse-grained scale, which can preserve some selected aspects of the longer time phenomena of the microscopic scale?
• How to construct appropriate coarse-grained dynamical schemes for multicomponent systems (for which some aspects of the equilibrium coarse-graining are also still under debate)?
To succeed in the above efforts requires a confluence of ideas from researchers working on different aspects of coarse-graining, such as mathematical issues, nonequilibrium statistical mechanics, developers of dynamical simulations of soft matter systems and researchers applying such simulations to materials of practical and fundamental interest.
Our workshop will bring together a unique combination of experts who recently developed a mathematical framework of coarse-graining (e.g., systematic coarse-graining of dynamics8, 9, 11, 12, thermostats10, heterogeneous multiscale modeling,13-16 equation-free modeling,17 Lattice-Boltzmann-18 and Multi-Particle-Collision-dynamics19, and simulation techniques for rare events) and practitioners, who applied computational techniques to collective phenomena in soft matter/polymers20 and chemistry and engineering.
Marcus Mueller ( Georg-August Uiversity Göttingen ) - Organiser
Friederike Schmid ( Johannes Gutenberg University Mainz ) - Organiser
Venkat Ganesan ( University of Texas at Austin ) - Organiser & speaker