Calculation of the contact value of the first‐ and second‐order terms in the perturbation expansion of the radial distribution function for the square‐well potential

1976 ◽  
Vol 64 (10) ◽  
pp. 4244-4245 ◽  
Author(s):  
D. Henderson ◽  
J. A. Barker ◽  
W. R. Smith
Keyword(s):  
Distribution Function ◽  
Radial Distribution Function ◽  
Radial Distribution ◽  
Perturbation Expansion ◽  
Second Order ◽  
Square Well

Perturbation Theory and the Triangular Well Potential

1975 ◽  
Vol 53 (1) ◽  
pp. 5-12 ◽  
Author(s):  
W. R. Smith ◽  
D. Henderson ◽  
J. A. Barker
Keyword(s):  
Free Energy ◽  
Distribution Function ◽  
Perturbation Theory ◽  
Radial Distribution Function ◽  
Radial Distribution ◽  
Order Term ◽  
Second Order ◽  
First Order ◽  
Triangular Well Potential

Accurate calculations of the second order term in the free energy and the first order term in the radial distribution function in the Barker–Henderson (BH) perturbation theory are presented for the triangular well potential. The BH theory is found to be fully satisfactory for this system. Thus, the conclusions of Card and Walkley regarding the accuracy of the BH theory are erroneous.

SQUARE-WELL FLUID AT LOW DENSITIES

1967 ◽  
Vol 45 (12) ◽  
pp. 3959-3978 ◽  
Author(s):  
J. A. Barker ◽  
D. Henderson
Keyword(s):  
Distribution Function ◽  
Correlation Function ◽  
Critical Temperature ◽  
Radial Distribution Function ◽  
Radial Distribution ◽  
Virial Coefficients ◽  
Hard Core ◽  
Direct Correlation Function ◽  
Virial Series ◽  
Square Well

Values for the radial distribution function and the direct correlation function at low densities and for the first five virial coefficients are obtained for a fluid of molecules interacting according to the square-well potential when the width of the attractive well is half the radius of the hard core. It is found that the higher-order coefficients are surprisingly large and, as a result, the virial series fails to converge even at temperatures and volumes significantly greater than the critical temperature and volume. Comparisons of these exact virial coefficients with those given by several approximate theories are made. Values are also given for the first five virial coefficients when the width of the attractive well is equal to the radius of the hard core.

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