
2
Some Basics on
Statistical Mechanics
In this chapter, we will introduce a number of basic concepts and expressions which
will be useful throughout the book. These include the virial theorem, the correlation
functions, the pressure, energy, and compressibility equations for monocomponent as
well as for multicomponent systems, and the static structure factor. All these matters
can be found in many textbooks on statistical mechanics, but it is convenient to review
them here for further reference.
2.1 VIRIAL THEOREM AND THE EQUATION OF STATE
Let us consider a three-dimensional system consisting of N molecules with mass m
interacting with each other by