A general equation of state for dense fluids

Parsafar, Gholamabbas; Farzi, Nahid; Najafi, Bijan

doi:10.1007/bf02575256

Cited by 18 publications

(15 citation statements)

References 22 publications

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“…In fact because of the near pressure-independency of liquid density, isotherms of a function of Z vs. a function of density are linear. This is proved by the existence of the afore-cited linear isotherms [13,14,30], all observed for liquid metals, and also for ordinary fluids [31][32][33], but none of these regularities results in a specific potential energy function.…”

Section: Methodsmentioning

confidence: 87%

Molecular dynamics simulation of potassium along the liquid-vapor coexistence curve

Eslami

Mozaffari

Moghadasi

2010

JICS

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The applicability of pair potential functions to liquid alkali metals is questionable. On the one hand, some recent reports in the literature suggest the validity of two-parameter pair-wise additive Lennard-Jones (LJ) potentials for liquid alkali metals. On the other hand, there are some reports suggesting the inaccuracy of pair potential functions for liquid metals. In this work, we have performed extensive molecular dynamics simulations of vapor-liquid phase equilibria in potassium to check the validity of the proposed LJ potentials and to improve their accuracy by changing the LJ exponents and taking into account the temperaturedependencies of the potential parameters. We have calculated the orthobaric liquid and vapor densities of potassium using LJ (12-6), LJ (8.5-4) and LJ (5-4), effective pair potential energy functions. The results show that using an LJ (8.5-4) potential energy function with temperature-independent parameters, İ and ı, is inadequate to account for the vapor-liquid coexistence properties of potassium. Taking into account the temperature-dependencies of the LJ parameters, İ(T) and ı(T), we obtained the densities of coexisting liquid and vapor potassium in a much better agreement with experimental data. Changing the magnitude of repulsive and attractive contributions to the potential energy function shows that a two-parameter LJ (5-4) potential can well reproduce the densities of liquid and vapor potassium. The results show that LJ (5-4) potential with temperature-dependent parameters produces the densities of liquid and vapor potassium more accurately, compared to the results obtained using LJ (12-6) and LJ (8.5-4) potential energy functions.

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Section: Methodsmentioning

confidence: 87%

Molecular dynamics simulation of potassium along the liquid-vapor coexistence curve

Eslami

Mozaffari

Moghadasi

2010

JICS

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“…(3), gives the correct asymptotic limit, predicting V = 0 at infinite pressure. This equation was later successfully applied by Parsafar et al [16] to a wide variety of dense liquids (polar, non-polar, hydrocarbons, hydrogen bonded, quantum fluids).…”

Section: Universal Equation Of Statementioning

confidence: 93%

“…Simulations have been carried out under isothermal conditions, in the range 2000-3000 K, and with pressures up to 20 GPa. The resulting p-V m -T surface has been interpreted according to the Parsafar and MasonEoS, originally developed for a variety of solids, but recently extended to liquids [16]. Finally, it was established that the ionic melt of HOAp follows some of the regularities found for liquids, namely: (i) the Tait-Murnaghan relation [17], which states that the isothermal bulk modulus, B T , is a linear function of pressure, B T = A + Bp, and (ii) the Parsafar-Mason [18] correlation, showing a linear dependence of (Z − 1)V 2 with the square of the density, ρ 2 (where Z is the compressibility factor).…”

Section: Introductionmentioning

confidence: 99%

Molecular dynamics simulations of molten calcium hydroxyapatite

Cruz¹,

Lopes²,

Calado³

2006

Fluid Phase Equilibria

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“…The dense system equation of state (DSEOS) is derived as [29] where ρ r = ρ/ρ c , v r = v/v c , and P r = P /P c are dimensionless variables. On the basis of the linear dependence of the isochoric heat capacity with temperature, the A 0 , A 1 , and A 2 parameters were derived as [29] A…”

Section: Using the Zeno Line To Derive The Temperature Dependencies Omentioning

confidence: 99%

“…On the basis of the linear dependence of the isochoric heat capacity with temperature, the A 0 , A 1 , and A 2 parameters were derived as [29] A…”

Section: Using the Zeno Line To Derive The Temperature Dependencies Omentioning

confidence: 99%

Analysis of Different EOSs in Predicting the Ideal Curve and Deriving the Temperature Dependencies of Their Parameters

Parsafar

Saydi

2004

International Journal of Thermophysics

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The regularity shown by different fluids along the contour of the ideal compressibility factor Z = P V /(RT ) = 1 in the temperature-density plane is used to test the accuracy of different equations of state and derive temperature dependencies of their parameters. For a wide range of pure fluids, this contour, known as the Zeno line, has been empirically observed to be nearly linear. The precision of the van der Waals (vdW) equation in predicting the Zeno line has been evaluated and shown that this equation predicts a linear relation between temperature and density on the Z = 1 contour, qualitatively. However, the line shows significant deviations from the experimental Zeno line. Experimental PVT data for CO 2 is used to obtain the temperature dependencies of the vdW parameters. The vdW equation with such temperature dependencies does not show a straight line for the Z = 1 contour. This means that the equation is not able to predict the Zeno line, both qualitatively and quantitatively. Also, the accuracy of the modified vdW equations in predicting the Zeno line has been investigated. It is shown that none of these equations can predict the Zeno line qualitatively. However, the predicted line on the Z = 1 contour given by some of these equations is near the experimental Zeno line. Assuming that the Zeno line must hold, the temperature dependence of the non-ideal thermal pressure, A , of the linear isotherm regularity as A = a + bT + c/T has been derived. Such a temperature dependence was confirmed by experimental data. The derived expression for A was used to obtain the temperature dependence of the thermal pressure coefficient, which is in accordance with experimental data. Also, the temperature dependencies of the parameters of the dense system equation of state

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A general equation of state for dense fluids

Cited by 18 publications

References 22 publications

Molecular dynamics simulation of potassium along the liquid-vapor coexistence curve

Molecular dynamics simulation of potassium along the liquid-vapor coexistence curve

Molecular dynamics simulations of molten calcium hydroxyapatite

Analysis of Different EOSs in Predicting the Ideal Curve and Deriving the Temperature Dependencies of Their Parameters

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