Long ranged interactions in computer simulations and for quasi-2D systems

Mazars, Martial

doi:10.1016/j.physrep.2010.11.004

Cited by 65 publications

(71 citation statements)

References 526 publications

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“…numerically 7,8,13 . As electrorheological fluids, use has been made of colloids with a dielectric constant different from that of the surrounding fluid 20,38 , which have induced dipole moments in electric field.…”

Section: Dipole Chainsmentioning

confidence: 99%

“…For example, the local electric field acting on a dipole is known to be different from the applied electric field in dielectrics and polar fluids 26,27 , where the difference is enlarged in highly polarizable systems. In contrast, a number of microscopic simulations have been performed on the effect of uniform magnetic field for systems of magnetic dipoles 7,8,28 .…”

Section: Introductionmentioning

confidence: 99%

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Applying electric field to charged and polar particles between metallic plates: Extension of the Ewald method

Takae

Ōnuki

2013

The Journal of Chemical Physics

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We develop an efficient Ewald method of molecular dynamics simulation for calculating the electrostatic interactions among charged and polar particles between parallel metallic plates, where we may apply an electric field with an arbitrary size. We use the fact that the potential from the surface charges is equivalent to the sum of those from image charges and dipoles located outside the cell. We present simulation results on boundary effects of charged and polar fluids, formation of ionic crystals, and formation of dipole chains, where the applied field and the image interaction are crucial. For polar fluids, we find a large deviation of the classical Lorentz-field relation between the local field and the applied field due to pair correlations along the applied field. As general aspects, we clarify the difference between the potential-fixed and the charge-fixed boundary conditions and examine the relationship between the discrete particle description and the continuum electrostatics.

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Section: Dipole Chainsmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Applying electric field to charged and polar particles between metallic plates: Extension of the Ewald method

Takae

Ōnuki

2013

The Journal of Chemical Physics

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“…The lattice sums in Eq.1 are computed with the Ewald method [41]. The Monte Carlo simulations are done at finite tempera- ture T in the canonical ensemble with a variable shape of S 0 , but at constant surface area.…”

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confidence: 99%

The melting of the classical two-dimensional Wigner crystal

Mazars¹

2015

EPL

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D--Solid-liquid transitions PACS 64.60.qe -General theory and computer simulations of nucleation PACS 64.60.an -Finite-size systems Abstract -We report an extensive Monte-Carlo study of the melting of the classical two dimensional Wigner crystal for a system of point particles interacting via the 1/r-Coulomb potential. A hexatic phase is found in systems large enough. With the multiple histograms method and the finite size scaling theory, we show that the fluid/hexatic phase transition is weakly first order. No set of critical exponents, consistent with a Kosterlitz-Thouless transition and the finite size scaling analysis for this transition, have been found.Like charged particles immersed in a homogeneous neutralizing background form crystals at low temperature [1][2][3] ; these crystals are called Wigner crystals after the seminal work of E.P. Wigner in 1934 on electrons in metals [1]. Since the original work of Wigner, Coulomb crystals have been observed in a large variety of systems: in plasma physics [4,5], in colloids science [6,7], in semiconductors [8][9][10] and in biology [7]. Two dimensional Wigner crystals are observed in complex plasmas [4,5], in electrons trapped on the surface of liquid Helium [11][12][13][14], in lasercooled 9 Be + ions confined in Penning traps [15], in inversion layer of semiconductors at low temperature [16]. Colloids and dusty plasmas are classical systems ; the classical regime for electrons and ions is defined, in absence of magnetic field, when the Fermi energy is small compared to interaction energy and temperature ; for surface electrons, it corresponds to low surface density [3,17,18]. The ground-state of the classical two dimensional Wigner crystal is known to be a triangular lattice [2,3,[19][20][21] and it is worthwhile to outline that the long ranged nature of the interaction in Coulomb systems does not fulfill the hypothesis of the Mermin theorem on the abscence of long ranged cristalline order in two dimensions [22]. For all experimental systems mentioned above, the study of the phase transition between the ordered Wigner crystal and the disordered fluid-like phases has peculiar importance. Not only for a better understanding of the structural properties of these systems, but also for the theoretical study of the two dimensional meltings [23][24][25][26][27][28][29][30][31][32][33][34][35][36][37][38][39][40]. In this letter, we report an extensive Monte Carlo study of the melting of the classical two dimensional Wigner crystal. The system is made of N charged point particles confined in a two dimensional plane ; periodic boundary conditions in two dimensions are used. The interaction energy between a pair of particles is the Coulomb energy V (r) = Q 2 /r with Q the charge of particles and r the distance in the plane between both particles. The charges of particles are neutralized by an uniform background of charge density σ 0 ; electroneutrality of the system reads as N Q + σ 0 S = 0 with S the surface of the simulation cell. The number density is noted ρ = N/S a...

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“…We use standard two-dimensional Ewald summation to incorporate long-ranged dipolar interactions. 51 For further details on simulations and their comparison with experiments see Appendix and the ESI † (Fig. S1).…”

Section: Comparison Of Experiments and Simulationsmentioning

confidence: 99%

Multidirectional colloidal assembly in concurrent electric and magnetic fields

et al. 2016

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a Dipolar interactions between nano-and micron sized colloids lead to their assembly into domains with well-defined local order. The particles with a single dipole induced by an external field assemble into linear chains and clusters. However, to achieve the formation of multidirectionally organized nano-or microassemblies with tunable physical characteristics, more sophisticated interaction tools are needed.Here we demonstrate that such complex interactions can be introduced in the form of two independent, non-interacting dipoles (double-dipoles) within a microparticle. We show how this can be achieved by the simultaneous application of alternating current (AC)-electric field and uniform magnetic field to dispersions of superparamagnetic microspheres. Depending on their timing and intensity, concurrent electric and magnetic fields lead to the formation of bidirectional particle chains, colloidal networks, and discrete crystals. We investigate the mechanistic details of the assembly process, and identify and classify the non-equilibrium states formed. The morphologies of different experimental states are in excellent correlation with our theoretical predictions based on Brownian dynamics simulations combined with a structural analysis based on local energy parameters. This novel methodology of introducing and interpreting double-dipolar particle interactions may assist in the assembly of colloidal coatings, dynamically reconfigurable particle networks, and bidirectional active structures.

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Long ranged interactions in computer simulations and for quasi-2D systems

Cited by 65 publications

References 526 publications

Applying electric field to charged and polar particles between metallic plates: Extension of the Ewald method

Applying electric field to charged and polar particles between metallic plates: Extension of the Ewald method

The melting of the classical two-dimensional Wigner crystal

Multidirectional colloidal assembly in concurrent electric and magnetic fields

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