1: Fluids
- Page ID
- 294271
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- 1.1: What is a Fluid?
- What is a fluid? Almost everything that we will discuss is soft matter under physiological temperature conditions: liquids and solutions, cytoplasm and cytosol, DNA and proteins in solution, membranes, micelles, colloids, gels... All of these materials can in some respect be considered a fluid.
- 1.2: Radial Distribution Function
- The radial distribution function, g(r), is the most useful measure of the “structure” of a fluid at molecular length scales. g(r) provides a statistical description of the local packing and particle density of the system, by describing the average distribution of particles around a central reference particle.
- 1.3: Excluded Volume
- One of the key concepts that arises from a particulate description of matter is excluded volume. Even in the absence of attractive interactions, at short range the particles of the fluid collide and experience repulsive forces. These repulsive forces are a manifestation of excluded volume, the volume occupied by one particle that is not available to another. This excluded volume gives rise to the structure of solvation shells that is reflected in the short-range form of g(r) and W(r).