Above:From left to right, the top row shows the morphology of a system with 10000 monomers and a box size of 64 (volume fraction of .02) for k=8 and T=.1kt after 500 time steps (left) and 5000 (right).  The bottom row contains the same conditions except the salt concentration has been changed to k=5.


Aggregation can be defined as the act of individual pieces of matter coming together as a whole.  The random aggregation of particles can be described by two cases.  One case, known as diffusion limited cluster aggregation (DLCA), is when a particle is so strongly attracted to a nearby aggregate or another particle that it sticks irreversibly during the aggregation process.  This type of aggregation leads to stringy, fractal like structures that aren't very compact and have a correlation number on average of 2, meaning each particle in the aggregating cluster has only two particles touching it.  The aggregates formed during DLCA have a fractal dimension of 1.8, which is representative of their less compact structure.  The other case, known as reaction limited cluster aggregation (RLCA), is where the particle doesn't irreversibly stick on its first encounter with another particle or aggregate, but instead takes multiple counters in order to stick.  These aggregates are not as stringy and are more compact, which can be seen by observing their average coordination number of 12 and a fractal dimension of 2.1.