Bridge function

The bridge functions are infinite series of irreducible diagrams $D_i$:

$B^{(2)}(r)={\rho }^2\frac{1}{2}{D}_1(r)+{\rho }^3[D_2(r)+D_3(r)]+{\rho }^4[...]+...$

and

$B^{(1)}(r)=\frac{1}{3}{B}^{(2)}(r)+{\rho }^3[\frac{1}{6}{D}_2(r)-\frac{1}{12}{D}_3(r)]+{\rho }^4[...]+...$

where $\rho$ is the density of the fluid

References

1. Jean-Marc Bomont and Jean-Louis Bretonnet "Approximative “one particle” bridge function B(1)(r) for the theory of simple fluids", Journal of Chemical Physics 126 214504 (2007)