Perturbation Theories for the Thermodynamic Properties of Fluids and Solids

250 Perturbation Theories for Fluids and Solids

n-mer fluid. In approximation AB, the bond length L is equal for dimers and the

n-mers, and n

m

, σ

m

, n

d

, and σ

d

are determined from the conditions that the surface

area and packing fraction must be equal for monomers, dimers, and n-mers. The

approximation AC considers the reduced bond length L

∗

for the dimers equal to that

of the n-mers and determines σ

m

, σ

d

, n

m

, and n

d

in the same way just described for

the AB approximation. The A, AB, and AC approximations, contrarily to the B and

C approximations, fulfil the condition that when L → 0then-mer fluid reduces to

a HS fluid, as it should be. A drawback common ...