  In this paper we give a method for constructing systematically all simple
2-connected graphs with n vertices from the set of simple 2-connected graphs
with n-1 vertices, by means of two operations: subdivision of an edge and
addition of a vertex. The motivation of our study comes from the theory of
non-ideal gases and, more specifically, from the virial equation of state. It
is a known result of Statistical Mechanics that the coefficients in the virial
equation of state are sums over labelled 2-connected graphs. These graphs
correspond to clusters of particles. Thus, theoretically, the virial
coefficients of any order can be calculated by means of 2-connected graphs used
in the virial coefficient of the previous order. Our main result gives a method
for constructing inductively all simple 2-connected graphs, by induction on the
number of vertices. Moreover, the two operations we are using maintain the
correspondence between graphs and clusters of particles.
