Thermodynamics of dipolar hard spheres with low-to-intermediate coupling constants

Elfimova, Ekaterina A.; Иванов, А. П.; Camp, Philip J.

doi:10.1103/physreve.86.021126

Cited by 31 publications

(39 citation statements)

References 41 publications

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“…In Ref. [24] it was shown that the LFE expressions containing expansions of B 2 , B 3 , and B 4 in terms of λ are superior to the traditional TPT results [22,23] for DHS fluids with λ 4 and ρσ 3 0.95.…”

Section: B Virial Coefficients For Dhss In An Applied Fieldmentioning

confidence: 99%

“…In Ref. [24], a new theory was developed from a logarithmic representation of the Helmholtz free energy F . For the case of DHSs in an applied field, this theory is based on the relation…”

Section: B Virial Coefficients For Dhss In An Applied Fieldmentioning

confidence: 99%

“…There are many theories of dipolar liquids, but among the most successful (for the thermodynamic properties of DHSs) is the thermodynamic perturbation theory (TPT) of Stell and co-workers [22,23]. In a recent study, the present authors constructed a new theory based on the virial expansion, which outperforms the TPT, but requires only the first few virial coefficients as input [24]. The theory is based on a logarithmic representation of the Helmholtz free energy, and hence it will be referred to as the logarithmic free energy (LFE) theory; it will be summarized briefly in Sec.…”

Section: Introductionmentioning

confidence: 99%

“…Numerical results are obtained using the Mayer-sampling method introduced by Singh and Kofke [34]. Next, the analytical results are incorporated in to various virial-type expressions for the thermodynamic functions, including the so-called perturbed virial expansion (PVE) developed by Nezbeda and co-workers [35][36][37], and the present authors' LFE theory [24]. The theoretical results for the equation of state are compared critically against Monte Carlo (MC) simulation results, and it is demonstrated that the LFE theory is superior for DHSs in an applied magnetic field.…”

Section: Introductionmentioning

confidence: 99%

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Thermodynamics of ferrofluids in applied magnetic fields

2013

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The thermodynamic properties of ferrofluids in applied magnetic fields are examined using theory and computer simulation. The dipolar hard sphere model is used. The second and third virial coefficients (B 2 and B 3 ) are evaluated as functions of the dipolar coupling constant λ, and the Langevin parameter α. The formula for B 3 for a system in an applied field is different from that in the zero-field case, and a derivation is presented. The formulas are compared to results from Mayer-sampling calculations, and the trends with increasing λ and α are examined. Very good agreement between theory and computation is demonstrated for the realistic values λ 2. The analytical formulas for the virial coefficients are incorporated in to various forms of virial expansion, designed to minimize the effects of truncation. The theoretical results for the equation of state are compared against results from Monte Carlo simulations. In all cases, the so-called logarithmic free energy theory is seen to be superior. In this theory, the virial expansion of the Helmholtz free energy is re-summed in to a logarithmic function. Its success is due to the approximate representation of high-order terms in the virial expansion, while retaining the exact low-concentration behavior. The theory also yields the magnetization, and a comparison with simulation results and a competing modified mean-field theory shows excellent agreement. Finally, the putative field-dependent critical parameters for the condensation transition are obtained and compared against existing simulation results for the Stockmayer fluid. Dipolar hard spheres do not undergo the transition, but the presence of isotropic attractions, as in the Stockmayer fluid, gives rise to condensation even in zero field. A comparison of the relative changes in critical parameters with increasing field strength shows excellent agreement between theory and simulation, showing that the theoretical treatment of the dipolar interactions is robust.

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Section: B Virial Coefficients For Dhss In An Applied Fieldmentioning

confidence: 99%

“…In Ref. [24], a new theory was developed from a logarithmic representation of the Helmholtz free energy F . For the case of DHSs in an applied field, this theory is based on the relation…”

Section: B Virial Coefficients For Dhss In An Applied Fieldmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Thermodynamics of ferrofluids in applied magnetic fields

2013

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“…As the system is cooled down, 0.5 ≥ T ≥ 0.2, particles start to self-assemble into small, disordered clusters. 37 At this T, thermal fluctuations are so relevant that the formed clusters do not have a clear chain-like shape and contain many defects. In this regime, defect cluster size distributions are monotonic and do not have any of the features found at low temperatures.…”

Section: A Identification Of the Defect Clusters And Their Spatial Cmentioning

confidence: 99%

Branching points in the low-temperature dipolar hard sphere fluid

Rovigatti

Kantorovich

Иванов

et al. 2013

The Journal of Chemical Physics

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Branching points in the low-temperature dipolar hard sphere fluid In this contribution, we investigate the low-temperature, low-density behaviour of dipolar hardsphere (DHS) particles, i.e., hard spheres with dipoles embedded in their centre. We aim at describing the DHS fluid in terms of a network of chains and rings (the fundamental clusters) held together by branching points (defects) of different nature. We first introduce a systematic way of classifying inter-cluster connections according to their topology, and then employ this classification to analyse the geometric and thermodynamic properties of each class of defects, as extracted from state-of-the-art equilibrium Monte Carlo simulations. By computing the average density and energetic cost of each defect class, we find that the relevant contribution to inter-cluster interactions is indeed provided by (rare) three-way junctions and by four-way junctions arising from parallel or anti-parallel locally linear aggregates. All other (numerous) defects are either intra-cluster or associated to low cluster-cluster interaction energies, suggesting that these defects do not play a significant part in the thermodynamic description of the self-assembly processes of dipolar hard spheres.

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Structure, Dynamics, and Thermodynamics of Ferrofluids

Camp

2017

Springer Proceedings in Physics

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A survey of recent work on the structure, dynamics, and thermodynamics of ferrofluids is given. The emphasis is on new theoretical descriptions and computer simulations of simple models of colloidal ferromagnetic nanoparticles, but some favourable comparisons with experiments are shown to justify the choices of models. The survey summarises combined theoretical and computational studies of field-induced microstructure in ferrofluids, magnetisation curves, static and dynamic initial magnetic susceptibilities, thermodynamic properties, and sedimentation profiles.

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Thermodynamics of dipolar hard spheres with low-to-intermediate coupling constants

Cited by 31 publications

References 41 publications

Thermodynamics of ferrofluids in applied magnetic fields

Thermodynamics of ferrofluids in applied magnetic fields

Branching points in the low-temperature dipolar hard sphere fluid

Structure, Dynamics, and Thermodynamics of Ferrofluids

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