Melting profile of cesium metal nanoclusters by molecular dynamics simulation

Ghatee, Mohammad Hadi; Shekoohi, Khadijeh

doi:10.1016/j.fluid.2012.05.001

Cited by 11 publications

(7 citation statements)

References 56 publications

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“…2 can be understood in terms of two different bindings in the molten alkali metals. 32 At the low molar volumes (high pressures and low temperatures), where the measured conductivity and thermodynamic state of the system agrees well with predictions from the NFE theory and the LIR, respectively, 5,6,27,32 the system is in a monoatomic state with a delocalized electron cloud over the entire system. In this state, increasing the molar volume further (decreasing pressure) leads to a smaller repulsion between ions and negative repulsive internal pressure, p i,R , which tend to increases the internal pressure.…”

Section: Internal Pressuresupporting

confidence: 65%

“…25 Also, Gupta potential has been used to study the melting of Na and Cs clusters in order to investigate the effects of the geometric and electronic magic numbers on the melting temperature as a function of cluster size. [26][27][28] The electronic structure of alkali metal fluids strongly depends on the thermodynamic state of the system. When Cs fluid expands, two transitions can occur, liquid-vapour and metal-non-metal one.…”

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confidence: 99%

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Molecular dynamic simulation study of molten cesium

Yeganegi

Moeini

Doroodi

2017

JSCS

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Molecular dynamics simulations were performed to study thermodynamics and structural properties of expanded caesium fluid. Internal pressure, radial distribution functions (RDFs), coordination numbers and diffusion coefficients have been calculated at temperature range 700-1600 K and pressure range 100-800 bar. We used the internal pressure to predict the metal--non-metal transition occurrence region. RDFs were calculated at wide ranges of temperature and pressure. The coordination numbers decrease and positions of the first peak of RDFs slightly increase as the temperature increases and pressure decreases. The calculated self-diffusion coefficients at various temperatures and pressures show no distinct boundary between Cs metallic fluid and its expanded fluid where it continuously increases with temperature. 682YEGANEGI, MOEINI and DOROODI performed in 1952 11 and the first momentous molecular dynamics (MD) simulation for Cs was performed in 2001. 12 The diffusion and shear-viscosity coefficients and velocity auto correlation function have been reported for Na, K, Rb and Cs near the melting point. [13][14][15] The simple but useful expressions for the relationship between structural and surface properties of liquid metals have been presented by employing the hard-sphere description near the melting point. 16,17 Also, MD simulations have been performed to calculate the structural and transport properties of liquid alkali metals by using reformed Morse potential near the melting point. 18 The embedded atom method potentials have been calculated for the alkali metals along the melting line of the metal and the discrepancy between the simulated energy, and the actual energy of the metal at high temperatures has been discussed. 19 Recently, thermodynamic quantities of the alkali metals 20 and their cluster size distributions 21 have been studied based on the static crystalline properties and using ab initio potential respectively.Gupta proposed a semi-empirical potential to study the metallic fluids by molecular dynamics. 22 The Gupta potential function has been applied successfully by many researchers to describe the structure and energy of Pb 23 , Ni, Ag, Au 24 and Cu-Au, Al, Zn and Cd clusters. 25 Also, Gupta potential has been used to study the melting of Na and Cs clusters in order to investigate the effects of the geometric and electronic magic numbers on the melting temperature as a function of cluster size. [26][27][28] The electronic structure of alkali metal fluids strongly depends on the thermodynamic state of the system. When Cs fluid expands, two transitions can occur, liquid-vapour and metal-non-metal one. 9 In fact, a high-density liquid metal is a conductor, while it becomes a non-metal insulator when turned into low-density vapour. Near the critical point the transition from a liquid metal to a non-metal takes place. 29 This transition implies that the nature of the particle interactions must change dramatically, from metallic to a van der Waals-type interaction. 30 The particle interactions in dense...

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Section: Internal Pressuresupporting

confidence: 65%

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confidence: 99%

Molecular dynamic simulation study of molten cesium

Yeganegi

Moeini

Doroodi

2017

JSCS

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“…Melting proceeds further by growth of surface liquid skin and growth/enhancement of a quasi-liquid interfacial region toward the remaining solid core of nanoparticles. Note that, although large crystalline Cs nanoclusters also exhibit surface and core melting, the heat capacity has only a single peak located at the homogeneous melting (i.e., melting of the core) based on the recent MD simulations of melting of Cs nanoclusters . Therefore, the nature of multipeak phenomenon observed for the heat capacity of melting of clusters of some materials is still unclear.…”

Section: Resultsmentioning

confidence: 99%

“…Note that, although large crystalline Cs nanoclusters also exhibit surface and core melting, the heat capacity has only a single peak located at the homogeneous melting (i.e., melting of the core) based on the recent MD simulations of melting of Cs nanoclusters. 38 Therefore, the nature of multipeak phenomenon observed for the heat capacity of melting of clusters of some materials is still unclear. On the other hand, although melting of simple clusters with LJ potential has been studied intensively (see refs 34 , 35 , 39, and references therein), much attention has been paid to the relatively small clusters containing up to hundreds of atoms.…”

Section: Resultsmentioning

confidence: 99%

Melting of Simple Monatomic Amorphous Nanoparticles

Hoang¹

2012

J. Phys. Chem. C

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Melting of the simple monatomic amorphous spherical nanoparticles has been studied via molecular dynamics (MD) simulation. Initial amorphous nanoparticles have been heated toward a normal liquid state to study a melting process with Lennard-Jones−Gauss interatomic potential [Engel, M.; Trebin, H.-R. Phys. Rev. Lett. 2007, 98, 225505]. Temperature dependence of various thermodynamic quantities of the system is found and discussed. Atomic mechanism of melting is monitored via analysis of the appearance/growth of the liquid-like atoms upon heating. Liquid-like atoms are determined by using the Lindemann melting criterion. In the premelting stage (i.e., below a glass transition temperature, T g ), liquid-like atoms occur first in the surface shell to form a quasi-liquid surface layer. Further heating leads to the formation of a purely liquid skin at the surface of nanoparticles together with a simultaneous occurrence/growth of liquid-like atoms in the remaining glassy matrix. Melting process proceeds further via propagation/growth of liquid-like configuration into the solid core. Liquid-like configuration includes a purely liquid skin, and liquid-like atoms occurred in the liquid−solid interfacial shell of nanoparticles. Total melting occurs at temperature much higher than T g . Heat capacity of the system exhibits a single peak at around a total melting point. We find a strong thermal hysteresis between amorphous nanoparticles obtained by heating/ cooling.

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“…On the other hand, the well-known system size dependence for the finite size can affect the result even under boundary condition, and depends asymptotically on the size as N –1/3 . This indeed has been found from studies on systems at nanoscale, over the size scale that their properties could correspond to the large size as dimension of bulk system.…”

Section: Discussionmentioning

confidence: 82%

Molecular Dynamics Simulation and Experimental Approach to the Temperature Dependent Surface and Bulk Properties of Hexanoic Acid

Ghatee

Ghanavati

Bahrami

et al. 2013

Ind. Eng. Chem. Res.

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For the first time, bulk and surface properties of hexanoic acid was simulated by classical molecular dynamics and compared with corresponding values we measured in the range of T = 298.15–373.15 K at ambient pressure. AMBER and optimized potential for liquid substance all atom (OPLS-AA) force fields plus our calculations for atoms charges enable simulating density, surface tension, and viscosity, as well as the bulk structural and orientational profile of molecules at the hexanoic acid/vapor interface. The simulated densities are in good agreement within 2.9%, and the simulated surface tension within 2% over the whole range of experimental measurement. On the basis of structural studies, the carboxylic headgroups form tight hydrogen bonding, whereas the alkyl chains loosely interact indication of a high electrostatic to van der Waals interaction ratio prevailing the liquid system. The simulated viscosities agree well at high temperatures with experiment, though the agreement is reduced at low temperatures. This can be attributed to describing hexanoic acid system with strong Coulombic interaction, H-bonding, and weak van der Waals interaction all by the same force field. Quite interestingly, the simulated density profile shows an enhancement at the interface characteristic of liquids of high anisotropic molecules and the ionic liquids.

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Melting profile of cesium metal nanoclusters by molecular dynamics simulation

Cited by 11 publications

References 56 publications

Molecular dynamic simulation study of molten cesium

Molecular dynamic simulation study of molten cesium

Melting of Simple Monatomic Amorphous Nanoparticles

Molecular Dynamics Simulation and Experimental Approach to the Temperature Dependent Surface and Bulk Properties of Hexanoic Acid

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