Universal equation of state for compressed solids

Parsafar, Gholamabbas; Mason, Edward A.

doi:10.1103/physrevb.49.3049

Cited by 82 publications

(84 citation statements)

References 30 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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“…The three parameters are the zero pressure values of the molar volume, the isothermal bulk modulus, B 0 T = V (∂p/∂V ) T , and the pressure derivative of the bulk modulus, B 0 T . Parsafar and Mason improved on the work of Vinet et al, and derived an equation which is both simpler and more accurate for a wide variety of substances, including some which undergo phase transitions [14]. Stressing that for solids under strong compression only the rather featureless repulsive branch of the binding-energy curve matters, they were able to show that pV 2 should be a quadratic function of the density, ρ = 1/V or, in reduced form (Eq.…”

Section: Universal Equation Of Statementioning

confidence: 97%

“…(For solids, c i = 0 [14].) Given the few number of isotherms and the accuracy of the MD data, the A i parameters were simply fitted to a quadratic expression on temperature, by putting d i = 0, Fig.…”

Section: Universal Equation Of Statementioning

confidence: 99%

“…Analogies between both polymorphic phases, namely a similar anisotropic response to applied pressure in the range 50 MPa-7.5 GPa, have been noted. An isothermal equation of state (EoS), originally proposed for solids under compression [14], was employed to describe the behaviour of the apatites under pressure, at room temperature; the precision was always better than 1%. New MD experiments which explicitly consider the influence of temperature on the monoclinic polymorphs (HOAp, ClAp), for several isobars, are now being carried out.…”

Section: Introductionmentioning

confidence: 99%

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Molecular dynamics simulations of molten calcium hydroxyapatite

Cruz¹,

Lopes²,

Calado³

2006

Fluid Phase Equilibria

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“…Some authors 28,29 pointed out that there is a restriction on Eq. ͑24͒ when it is applied to high-pressure phase solids under low-pressure conditions.…”

Section: ͑25͒mentioning

confidence: 99%

Semiempirical pressure-volume-temperature equation of state: MgSiO3 perovskite is an example

Garai

2007

Journal of Applied Physics

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Simple general formula describing the pressure-volume-temperature relationships ͑p-V-T͒ of elastic solids is constructed from theoretical considerations. The semiempirical equation of state ͑EOS͒ was tested to experiments of perovskite 0 -109 GPa and 293-2000 K. The parameters providing the best fit are B 0 = 267.5 GPa, V 0 = 24.284 cm 3 , ␣ 0 = 2.079ϫ 10 −5 K −1 , ‫ץ‬B 0 / ‫ץ‬p = 1.556, and ‫␣ץ‬ 0 / ‫ץ‬p = −1.098ϫ 10 −7 K −1 GPa −1 . The root-mean-square deviations ͑RMSDs͒ of the residuals are 0.043 cm 3 , 0.79 GPa, and 125 K for the molar volume, pressure, and temperature, respectively. These RMSD values are in the range of the uncertainty of the experiments, indicating that the five-parameter semiempirical EOS correctly describes the p-V-T relationships of perovskite. Separating the experiments into 200 K ranges the semiempirical EOS was compared to the most widely used finite strain, interatomic potential, and empirical isothermal EOSs such as the Birch-Murnaghan, the Vinet, and the Roy-Roy, respectively. Correlation coefficients, RMSDs of the residuals, and Akaike Information Criteria were used for evaluating the fitting. Based on these fitting parameters under pure isothermal conditions the semiempirical p-V EOS is slightly weaker than the Birch-Murnaghan and Vinet EOSs; however, the semiempirical p-V-T EOS is superior in every temperature range to all of the investigated conventional isothermal EOSs.

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Universal equation of state for compressed solids

Cited by 82 publications

References 30 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

Semiempirical pressure-volume-temperature equation of state: MgSiO3 perovskite is an example

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