J. Phys. Soc. Jpn. 70 (2001) pp. 1979-1985 |Next Article| |Table of Contents|
|Full Text PDF (155K)| |Buy This Article|
The Direct Correlation Function and Its Interpretation via the Linear Isotherm Regularity
Department of Chemistry, Faculty of Basic Sciences, Mazandaran University, Babolsar, Iran
1Department of Chemistry, Isfahan University of Technology, Isfahan, 84154, Iran
(Received November 10, 2000)
The contributions of all non-ideally effects which arise from excluded volume, attractive and repulsive forces have been separated and investigated in the direct correlation function, DCF, using the Linear Isotherm Regularity, LIR for dense fluids. In such away we have shown that the core of the DCF (0<r<σ) is related to the geometric effect which arises from the excluded volume, while the intermolecular interactions have an important role in the tail (σ<r<∞). Also mathematical expressions for the core and tail of the DCF have been presented via the bulk modulus and the LIR. These new expressions beside of satisfying the experimental DCF can also generate the structural factor of fluids. The other issue that we discuss in this article and should be noticed separately, is the effective pair potential. The effective pair potential is the intermolecular pair interactions in presence of the other molecules of the system. We have shown that the well depth of such an effective pair potential is shallower than that of the isolated pair which is in accordance with the reported results in the literatures. Our results suggest that the net effect of the medium on interactions between two molecules is positive (repulsion).
©2001 The Physical Society of Japan
KEYWORDS:direct correlation function, effective pair potential, linear isotherm regularity, structure factor
- S. Kambayashi and Y. Hiwatari:
J. Non-Cryst. Solids 156–158 (1993) 80[CrossRef].
- L. Goldstein:
Phys. Rev. 48 (1951) 466[APS].
- D. A. McQuarri: Statistical Mechanic (Harper and Row, New York, 1988).
- A. S. Ornstein and F. Zernick: Proc. Akad. Sci. 17 (1914) 793.
- F. Zernick: Proc. Akad. Sci. 18 (1916) 1520.
- T. M. Reed and K. E. Gubbins: Applied statistical Mechanics (McGraw-Hill, New York, 1973).
- M. E. Fisher:
J. Math. Phys. 5 (1964) 944[CrossRef].
- L. Verlet:
Phys. Rev. 165 (1968) 201[APS].
- C. A. Croxton: Introduction to Liquid State Physics (John Wiley, New York, 1978).
- G. A. Parsafar: J. Islamic Repub. Iran 2 (1991) 111.
- G. A. Parsafar and E. A. Mason:
J. Phys. Chem. 97 (1993) 9048[CrossRef].
- J. Weeks, D. Chandler and H. C. Anderson:
J. Chem. Phys. 54 (1971) 5237[AIP Scitation].
- S. Alavi, G. A. Parsafar and B. Najafi: Int. J. Thermophys. 16 (1995) 1421.
- G. S. Rushbrooke and H. I. Scoins: Proc. R. Soc. London Ser. A 216 (1953) 203.
- P. G. Mikolaj and C. J. Ping:
J. Chem. Phys. 46 (1966) 1412[AIP Scitation].
- R. B. Stewart and R. T. Jacobsen: J. Phys. Chem. Ref. Data 18 (1989) 640.
- J. Millant, J. H. Dymond and F. Castro: Transport Properties of Fluids (Cambridge University Press, 1996).
- R. S. Berry, S. A. Rice and J. Ross: Physical Chemistry (John Wiley, New York, 1980).
- G. C. Maitland, M. Rigby, E. B. Smith and W. A. Wakeham: Intermolecular Forces (Claredom Press, Oxford, 1981).
- J. O. Hirschfelder: Intermolecular forces (John Wiley, New York, 1967).
- E. Keshavarzi and G. A. Parsafar:
J. Phys. Chem. B 103 (1999) 6584[CrossRef].
- G. A. Parsafar and E. Keshavarzi:
Bull. Chem. Soc. Jpn. 73 (2000) 2445[CrossRef].
- E. Keshavarzi, G. A. Parsafar and B. Najafi: Int. J. Thermophys. 20 (1999) 643.