Kirkwood-Buff formula

Statistical mechanics gives relationships between the distribution functions and the bulk properties of fluids. The total internal energy of a fluid is given by the energy equation, the pressure is given by the virial equation, and the isothermal compressibility is given by the compressibility equation, see e. g.. Ref. 11. Through the Kirkwood-Buff formulas (0,... 

The liquid-vapor surface tension was calculated using the Kirkwood-Buff formula which in the geometry used in our system is given by [41]... 

The interfacial tension 7 is given by the relation (4)derived from the Kirkwood-Buff formula . 

Other approaches for computing the surface tension start from the statistical mechanical expression for the Helmholtz free energy or for the pressure. The Kirkwood-Buff formula for the surface tension of a liquid/vapor interface of an atomic liquid described by the pair potential approximation is ... 

The compressibility of a salt solution is given by the Kirkwood-Buff formula" as... 

Here [5], the molecular distribution functions were calculated by linearization of a generalized form of Kirkwood s integral equation [12, 13] and the increase in surface tension was computed from the molecular theory of Buff [14, 15] for this property. The ions were taken as point charges. The singlet and pair distribution functions were evaluated for very dilute ionic solutions. Then they were introduced into the statistical mechanical formulas for surface tension. 

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