A short description of DL_POLY

Smith, William R.; Todorov, Ilian T.

doi:10.1080/08927020600939830

Cited by 232 publications

(157 citation statements)

References 34 publications

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“…The MD simulations of the self-diffusivities were carried out with the DLPOLY code [6] for a variety of molecular loadings up to saturation limits. The crystallographic data are taken from literature sources [7].…”

Section: Molecular Simulation Methodologymentioning

confidence: 99%

Loading Dependence of Self‐Diffusivities of Gases in Zeolites

Krishna

Baten

2007

Chem Eng & Technol

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Experimental data on the self-diffusivities, D i,self , of a variety of gases (CH 4 , N 2 , Kr, C 2 H 6 , and C 3 H 8 ) in three different zeolites, LTA, FAU, and MFI, show different dependences on the molar loading, q i . In LTA, D i,self appears to increase with q i for all molecules except N 2 . In FAU and in MFI the D i,self shows a sharp decrease with increasing q i . In order to gain insights into the causes behind the loading dependences, molecular dynamics (MD) simulations were carried out to determine the self-diffusivities of seven gases (CH 4 , N 2 , Kr, C 2 H 6 , C 3 H 8 , Ar, and Ne) in six different all-silica zeolite structures (MFI, AFI, FAU, CHA, DDR, and LTA). The simulation results show that the variation of D i,self with q i is determined by a variety of factors that include molecular size and shape, and degree of confinement within the zeolite. For one-dimensional channels (AFI) and intersecting channel structures (MFI), the D i,self invariably decreases with increasing q i . For zeolite structures that consist of cages separated by windows (FAU, CHA, DDR, LTA), the size of the windows is an important determinant. When the windows are wide (FAU), the D i,self decreases with q i for all molecules. If the windows are narrow (CHA, DDR and LTA), the D i,self often exhibits a sharp increase with q i , reaches a maximum and reduces to near-zero values at saturation. The sharpness with which D i,self increases with q i , is dictated by the degree of confinement at the window. Weakly confined molecules, such as Ne, do not exhibit an increase of D i,self with q i .

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Section: Molecular Simulation Methodologymentioning

confidence: 99%

Loading Dependence of Self‐Diffusivities of Gases in Zeolites

Krishna

Baten

2007

Chem Eng & Technol

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“…Classical molecular dynamics simulations were performed using the DL_POLY 2.16 package (Smith and Todorov 2006). The Verlet algorithm was used to integrate the equations of motion (van Gunsteren and Berendsen 1990;Verlet 1967), the Ewald summation method was employed to calculate the long-range electrostatic interactions for the fluid (van Gunsteren and Berendsen 1990; Woodcock and Singer 1971), and the Nosé-Hoover thermostat was used to control the temperature (Nosé 1984).…”

Section: Molecular Dynamicsmentioning

confidence: 99%

Behavior of ethylene and ethane within single-walled carbon nanotubes. 1-Adsorption and equilibrium properties

Cruz

Müller

2009

Adsorption

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Endohedral adsorption properties of ethylene and ethane onto single-walled carbon nanotubes were investigated using a united atom (2CLJQ) and a fully atomistic (AA-OPLS) force fields, by Grand Canonical Monte Carlo and Molecular Dynamics techniques. Pure fluids were studied at room temperature, T = 300 K, and in the pressure ranges 4 × 10 −4 < p < 47.1 bar (C 2 H 4 ) and 4 × 10 −4 < p < 37.9 bar (C 2 H 6 ). In the low pressure region, isotherms differ quantitatively depending on the intermolecular potential used, but show the same qualitative features. Both potentials predict that ethane is preferentially adsorbed at low pressures, and the opposite behavior was observed at high loadings. Isosteric heats of adsorption and estimates of low pressure Henry's constants, confirmed that ethane adsorption is the thermodynamically favored process at low pressures. Binary mixtures of C 2 H 4 /C 2 H 6 were studied under several (p, T ) conditions and the corresponding selectivities towards ethane, S, were evaluated. Small values of S < 4 were found in all cases studied. Nanotube geometry plays a minor role on the adsorption properties, which seem to be driven at lower pressures primarily by the larger affinity of the alkane towards the carbon surface and at higher pressures by molecular volume and packing effects. The fact that the selectivity towards ethane is similar to that found earlier on carbon slit pores and larger diameter nanotubes points to the fact that the peculiar 1-D geometry of the nanotubes provides no particular incentive for the adsorption of either species.

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“…7, the partial VDOS have been computed and are shown on most at high frequency (27-37 THz, symmetric and antisymmetric stretching modes) and at intermediate frequency (22 THz, O-Si-O bending mode). BO atoms predominant contributions occur at high frequency (29)(30)(31)(32)(33)(34)(35)(36)(37) THz, symmetric stretching modes) and at low and intermediate frequency (0-26 THz, Si-BO-Si bending mode and symmetric stretching mode). The contribution of NBOs differs from the one of the BOs because of the decreased number of O-Si stretching modes and of the softening of the Si-NBO-Na bending mode as compared to the Si-BO-Si mode.…”

Section: Vibrational Density Of Statesmentioning

confidence: 99%

“…Classical Molecular Dynamics simulations were performed using the DLPOLY package 35 . The equations of motion were integrated with the Verlet-Leapfrog algorithm, using a timestep of 2.0 fs.…”

Section: Simulation Detailsmentioning

confidence: 99%

Structural, vibrational, and thermal properties of densified silicates: Insights from molecular dynamics

Bauchy

2012

The Journal of Chemical Physics

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Structural, vibrational and thermal properties of densified sodium silicate (NS2) are investigated with classical molecular dynamics simulations of the glass and the liquid state. A systematic investigation of the glass structure with respect to density was performed. We observe a repolymerization of the network manifested by a transition from a tetrahedral to an octahedral silicon environment, the decrease of the amount of non-bridging oxygen atoms and the appearance of three-fold coordinated oxygen atoms (triclusters). Anomalous changes in the medium range order are observed, the first sharp diffraction peak showing a minimum of its full-width at half maximum according to density. The previously reported vibrational trends in densified glasses are observed, such as the shift of the Boson peak intensity to higher frequencies and the decrease of its intensity. Finally, we show that the thermal behavior of the liquid can be reproduced by the Birch-Murnaghan equation of states, thus allowing us to compute the isothermal compressibility.

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A short description of DL_POLY

Cited by 232 publications

References 34 publications

Loading Dependence of Self‐Diffusivities of Gases in Zeolites

Loading Dependence of Self‐Diffusivities of Gases in Zeolites

Behavior of ethylene and ethane within single-walled carbon nanotubes. 1-Adsorption and equilibrium properties

Structural, vibrational, and thermal properties of densified silicates: Insights from molecular dynamics

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