ABSTRACT
This chapter presents examples of common pair interaction potentials for spherical particles and gives an intuitive introduction to distribution functions in homogeneous bulk fluids like the radial distribution function, its higher order analogues and the relationships between them. It explains the concept of structure factor, which is important in scattering experiments, is introduced and its relationship to distribution functions. The pair distribution function of a bulk fluid can be experimentally determined by X-ray or neutron scattering experiments and for inhomogeneous fluids one can determine the structure on both singlet and pair distribution levels by such techniques. A computer simulation of a fluid is a numerical method to calculate various statistical mechanical properties of the system. In density functional theory, one starts from an approximate expression for the free energy of a system and then obtains distribution functions and thermodynamical properties by taking various derivatives.
