
346 Perturbation Theories for Fluids and Solids
with
K
n
=
k
B
T
(
2
n
λ
0
)
3
, (10.20)
I
n,i
=
ρ
0
exp
−G
n,i
(
x, ρ
)
K
n
dx, i = s, l, (10.21)
G
n,i
(
x, ρ
)
=
¯
f
∗
n,i
(
T, ρ +x
)
+
¯
f
∗
n,i
(
T, ρ −x
)
2
−
¯
f
∗
n,i
(
T, ρ
)
, i = s, l, (10.22)
¯
f
∗
n,l
(
T, ρ
)
= f
∗
n−1
(
T, ρ
)
+aρ
2
, (10.23)
¯
f
∗
n,s
(
T, ρ
)
= f
∗
n−1
(
T, ρ
)
+b
a
2
R
2
n
λ
0
2
ρ
2
, (10.24)
where
ρ
max
is the highest density allowed to the fluid
f
∗
n
(T, ρ) is given by Equation 10.6
R is the effective range of the attractive interaction obtained from
R
2
=
1
3
u
att
(
r
)
r
2
dr
u
att
(
r
)
dr
, (10.25)
and b is a parameter.
The theory was applied by Lue and Prausnitz (1998a,b) to pure fluids and
mixtures, respectively, with λ
0
and b treated as adjustable parameters, and extended ...