摘要:

In theory all the information regarding the three dimensional structure of a liquid is contained in the pair distribution functiong(r)or, equivalently, the structure factorA(Q), for a system with purely pairwise additive potentials. RMC is a method for modelling the structures of disordered systems based on the experimentally measured structure factor(s). We have performed some theoretical tests of the method, using input data calculated from simulations for various systems, which show that RMC does indeed work successfully if the potentials are pairwise additive. In cases where they are not then the imposition of constraints, e.g. modelling molecular systems with molecules rather than atoms, can enable the three dimensional structure to be determined. When the potentials are very complex, which usually makes the problem unsuitable for MC or MD simulations, RMC with constraints is still a valuable way of distinguishing between various structural possibilities.

ISSN:0031-9104    

DOI:10.1080/00319109108030643

出版商:Taylor & Francis Group    

年代:1991

数据来源: Taylor

摘要:

Excess molar volumesvEhave been measured for the binary liquid mixtures of propyl ethanoate with fiven-alkanes (n-hexane,n-heptane,n-octane,n-nonane andn-decane) at 298.15 and 308.15 K, using an Anton Paar densimeter. All the mixtures studied present positivevEvalues that increase with the length of the chain of the alkane and with the temperature. The experimental results are compared with the predictions of the Nitta—Chao model.

ISSN:0031-9104    

DOI:10.1080/00319109108030644

出版商:Taylor & Francis Group    

年代:1991

数据来源: Taylor

摘要:

Expressions for the second and fourth frequency sum rules of the velocity auto-correlation function have been obtained for an isotopic fluid. These expressions and Mori memory function formalism have been used to study the influence of the particle mass and mole fraction on the self diffusion coefficient. Our results confirm the weak mass dependence of the self diffusion. The influence of the mole fraction of the light particles on the self diffusion constant has been found to increase for the larger particle mass.

ISSN:0031-9104    

DOI:10.1080/00319109108030645

出版商:Taylor & Francis Group    

年代:1991

数据来源: Taylor

摘要:

Experimental solubilities are reported for anthracene in binary mixtures containing ethyl acetate or diethyl adipate withn-hexane,n-heptane,n-octane, cyclohexane, methylcyclohexane and isooctane at 25°C. Results of these measurements, combined with estimates for the excess Gibbs free energies of the binary solvents, are used to evaluate equilibrium constants for presumed anthracene-ethyl acetate and anthracene-diethyl adipate molecular complexes using the Extended Nearly Ideal Binary Solvent model. A single association constant was needed for each assumed complex in order to describe the experimental data to within an average deviation of 2%, though the numerical value did vary with inert hydrocarbon cosolvent. Poor estimates for the binary Gibbs free energies contributed significantly to the equilibrium constant variation.

ISSN:0031-9104    

DOI:10.1080/00319109108030646

出版商:Taylor & Francis Group    

年代:1991

数据来源: Taylor

摘要:

The conformal model for binary liquids is extended to the case when the interaction energies are linear in the concentration,c. It is found that a suitably definedc-dependent ordering energywis the single most important indication of the general character of the alloy, in particular of the behaviour of the excess free energy ΔFXSand of the concentration fluctuation functionScc. There are three cases:1.wis of fixed sign and varies by less than a factor of 2. Then ΔFXSandScc—c(1 -c) both have opposite sign fromw. The latter functions are largest (absolutely) in roughly the same region ofc.wchanges sign. Then ΔFXSandScc—c(1 -c) are of opposite sign fromwat each end of the diagram (much as one would expect on the basis of I).wis of fixed sign but varies by more than a factor of 2. Then ΔFXSis of opposite sign fromwandScc—c(1 -c) is mainly so. The latter function is, however, (marginally) of the same sign aswin a limited range of c at the end wherew(and ΔFXS) is absolutely smallest. The alloy system Li-Mg appears to be of this type.

ISSN:0031-9104    

DOI:10.1080/00319109108030647

出版商:Taylor & Francis Group    

年代:1991

数据来源: Taylor

摘要:

In this work we have used Enskog theory to evaluate transport properties ind-dimensional hard spheres. In order to carry out this study we have made use of the relation between the compressibility factorZand the ratioXE/X0, whereXEis the Enskog value for a transport property andX0is that corresponding to a dilute gas. From the available numerical data forZin simulation experiences, we have calculated the aforementioned ratio for the diffusion coefficientD, the shear viscosity coefficient η, the bulk viscosity coefficient η and the thermal conductivity coefficient λ. This calculation has been extended to hard disks (d= 2), hard spheres (d= 3) and hard hyperspheres (d= 4,5) in the maximum allowable range of densities. We have also tested the suitability of some algebraic equations of state proposed for such bodies by comparing their respective values forXE/X0. Finally, we have obtained numerical values for the ratioD/DEin the casesd= 4,5. The behavior is similar to that of hard spheres.

ISSN:0031-9104    

DOI:10.1080/00319109108030648

出版商:Taylor & Francis Group    

年代:1991

数据来源: Taylor

摘要:

Bulk viscosity and mutual coefficients of hard sphere (HS) mixtures predicted by kinetic theory are compared with molecular dynamics (MD) results. While for the mutual diffusion only the isotopic 2-component system is considered, for the bulk viscosity, both isotopic and systems composed of differently sized HS's are investigated. The results are interesting in two respects:1.for the isotopic mixture, value and concentration dependence of the mutual diffusion coefficient given by kinetic theory agree well with the ‘exact’ MD data.for mixtures composed of differently sized particles, kinetic theory predicts slightly higher bulk viscosity compared with the MD data, but gives correct trends for the concentration dependence.

ISSN:0031-9104    

DOI:10.1080/00319109108030649

出版商:Taylor & Francis Group    

年代:1991

数据来源: Taylor

摘要:

The “effective potential” for each system, nitrogen, argon, krypton, xenon, methane, benzene, carbon tetrachloride, carbon disulfide,n-hexane and cyclohexane was calculated by using the Clausius-Mossotti, Onsager and Kirkwood reaction fields with Lennard-Jones and Kihara potential parameters assumed. It was found that the Kirkwood reaction field with an assumed Kihara potential is a useful technique to study interactions arising due to physical association and chemical bonding.

ISSN:0031-9104    

DOI:10.1080/00319109108030650

出版商:Taylor & Francis Group    

年代:1991

数据来源: Taylor

摘要:

The inhomogeneous electron cloud in atomic ions ‘confined’ in hot plasmas and subjected to high static electric fields is studied, because of a body of experimental data on multiphoton ionization. In particular, the canonical (Bloch) density matrix is obtained in closed form for independent electrons moving in a static electric field of arbitrary strength and confined by a harmonic oscillator potential. To bring the model into contact with atoms in plasmas, the oscillator force constant is connected with the plasma density. For non-degenerate electrons an ‘atomic’ potential is included, by means of the Thomas—Fermi (TF) method. In an Appendix, a fully non-local theory is then developed which transcends this TF approximation. Simple numerical examples are presented for realistic values of field, temperature and plasma density.

ISSN:0031-9104    

DOI:10.1080/00319109108030651

出版商:Taylor & Francis Group    

年代:1991

数据来源: Taylor

摘要:

The longitudinal and bulk viscosity of the fluid Argon is calculated using its relation with self diffusion coefficient. This relation was derived by developing the relation between coherent and incoherent scattering functions. The results obtained are compared with recent simulation data of bulk viscosity. A good agreement is achieved for a wide range of temperatures at the triple point density. Our results successfully explain the increase in bulk viscosity with decrease in temperature near the triple point. The validity of the relation between diffusion and longitudinal viscosity is also tested for liquid metals. The results obtained for liquid metals of the longitudinal viscosity, at their melting points, are not found to be in agreement with experimental results. A relation between thermal conductivity and self-diffusion coefficient is proposed.

ISSN:0031-9104    

DOI:10.1080/00319109108030652

出版商:Taylor & Francis Group    

年代:1991

数据来源: Taylor