Soft matter: what is it?
The definition of soft matter encompasses a broad range of systems, from small molecules such as water to mesoscopic or macroscopic objects. They can be of natural origin, as proteins, DNA and lipid membranes, or artificial materials such as polymeric plastics. They can be passive as a piece of rubber, or active as a single enzyme or a swarm of bacteria. In all cases, what makes soft matter so diverse and fascinating is the interplay of properties and processes occurring at different length and time scales.
The theoretical and computational study of soft matter systems thus faces the challenge of taking into explicit account details and phenomena whose typical sizes and time scales are often separated by several orders of magnitude. A correspondingly wide spectrum of methods, techniques and models has been developed to tackle the soft matter zoo and gain quantitative understanding of its properties.
The scope of this course is to provide the students with the basic tools required by the computer-aided investigation of soft matter systems. The topic will be introduced starting from an intuitive, then progressively more formal definition of soft matter; the main classes of soft matter systems will be presented, and the general characteristics will be described. The theoretical tools necessary to the quantitative study of these systems will be recapped or explained, covering selected elements of thermodynamics, statistical mechanics, and computer simulation, whose role in the present context will be made clear through specific examples and applications. This will provide the tailored background for the discussion of soft matter modelling, i.e. the ensemble of techniques aimed at the generation of a computer model of a system and its usage in a simulation or other types of algorithmic analysis. A considerable segment of the course will be devoted to coarse-graining, that is, the (systematic) process of resolution reduction starting from a higher-resolution model. The most common and popular techniques will be presented, as well as some specific approaches developed to tackle a particular problem or system. Subsequently, the focus will be posed on enhanced sampling methods, whose usage is often a necessary prerequisite to overcome the difficulties inherent in the complex free energy landscapes that typically characterise soft matter systems. Finally, a few lectures will be devoted to the discussion of advanced modelling and simulation techniques that are currently at a fundamental research stage.
The course takes place in the second semester. Please refer to the ESSE3 webpage of the course for further details.