Simple Hard-Disk Monolayer Isotherms with Phase Transitions'

SIMPLE HARPDISKMONOLAYER ISOTHERMS WITH PHASE TRANSITIONS

and

(binomial approximation) Combining ey. 15, 16, and 17 and evaluating the resulting equation numerically

pv rb

- = 6

2.80

-

ii.95€ ~

kT

while the experimental result islo*ll

Discussion In this study we have shown that a free volurne partition function is obtained from Mayer’s theory of im-

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perfect gases when there is a hard sphere cutoff in the pairwise potential. The present approach gave a “van der Waals-like” equation of state similar to one developed by Hirschfelder, Stevenson, and E y r i r ~ g . ~ It is hoped that eq. 13 will find some utility as an