STRUCTURES AND DYNAMICS OF SMALL ALKALI-HALIDE CLUSTERS

1996 ◽  
Vol 03 (01) ◽  
pp. 347-351 ◽  
Author(s):  
V.K.W. CHENG ◽  
J.P. ROSE ◽  
R.S. BERRY
Keyword(s):  
Molecular Dynamics ◽  
Phase Behavior ◽  
Alkali Halide ◽  
Ionic Radius ◽  
Stable Form ◽  
Constant Energy ◽  
Large Ring ◽  
Close Packed Structure ◽  
Packed Structure

The structure and phase behavior of small alkali-halide clusters were studied by constant-energy molecular dynamics and optimization. Premelting was found for ( KCl )n, n=6, 9, 12. A correlation of the energy of a number of alkali-halide clusters and their relative ionic radius was made to establish the condition for the preference of a given type of isomers as the more stable form. The isomerization dynamics of large ring-like LiBr, i.e., folding of larger rings to smaller ones with cube-like or close-packed structure, is consistent with the correlation.

scholarly journals Role of halogen substituents in a series of polymorphic 2,5-diamino-3,6-dicyanopyrazine derivatives with highly flexible groups

2017 ◽  
Vol 232 (5) ◽  
pp. 395-405 ◽  
Author(s):  
Yoko Akune ◽  
Risa Hirosawa ◽  
Atsushi Koseki ◽  
Shinya Matsumoto
Keyword(s):  
Crystal Structure ◽  
Crystal Structures ◽  
Electrostatic Interactions ◽  
Crystal Structure Analysis ◽  
Stable Form ◽  
Thermally Stable ◽  
Close Packed Structure ◽  
Packed Structure ◽  
Stable Forms ◽  
Metastable Forms

AbstractThe crystal structures of the ortho-X-benzyl derivatives, where X=F, Cl, Br, I, and Me, of 2,5-bis(N,N-dibenzylamino)-3,6-dicyanopyrazine dyes (C34H24N6X4) were analysed to evaluate the effect of a systematic series of structures on the occurrence of polymorphism. Detailed crystal structure analysis indicated that the thermally stable forms of the polymorphic derivatives (Cl and Br derivatives) were close-packed, whereas those of the non-polymorphic derivatives (F and I derivatives) were stabilised by an intermolecular interaction involving the ortho-substituents. In the thermally metastable forms of the polymorphic derivative, halogen-halogen and halogen-nitrogen interactions contributed to the stabilisation of these crystals in the same way as the thermally stable form of the non-polymorphic derivatives. This indicated that the ease of polymorph occurrence would require an appropriate balance between the crystal energy of the close-packed structure and that of the crystal structure generated mainly by the electrostatic interactions involving the halogens in these halogenated pyrazine derivatives. In addition, the similar tendency of the occurrence of polymorphs in these halogenated pyrazine derivatives was found in 19 sets of halogenated compounds having known crystal structures of F, Cl, Br and I derivatives including at least one polymorphic derivative in the crystal structure database.

Phase behavior of cationic and anionic surfactants at low concentrations

1992 ◽  
Vol 50 (1) ◽  
pp. 694-695
Author(s):  
E. Naranjo
Keyword(s):  
Phase Behavior ◽  
Structural Characterization ◽  
Dynamic Systems ◽  
Anionic Surfactants ◽  
Intermolecular Forces ◽  
Stable Form ◽  
Surfactant Mixtures ◽  
Low Concentrations ◽  
Cationic And Anionic Surfactants ◽  
General Method

Equilibrium vesicles, those which are the stable form of aggregation and form spontaneously on mixing surfactant with water, have never been demonstrated in single component bilayers and only rarely in lipid or surfactant mixtures. Designing a simple and general method for producing spontaneous and stable vesicles depends on a better understanding of the thermodynamics of aggregation, the interplay of intermolecular forces in surfactants, and an efficient way of doing structural characterization in dynamic systems.

Encapsulation of α-Tocopherol in Large-ring Cyclodextrin Containing 26 α-D-Glucopyranose Units: A Molecular Dynamics Study

2021 ◽  
pp. 116802
Author(s):  
Khanittha Kerdpol ◽  
Bodee Nutho ◽  
Kuakarun Krusong ◽  
Rungtiva P. Poo-arporn ◽  
Thanyada Rungrotmongkol ◽  
...  
Keyword(s):  
Molecular Dynamics ◽  
Large Ring

scholarly journals Molecular Dynamics Simulation of Zener Pinning by Differently Shaped and Oriented Particles

2021 ◽  
Vol 8 ◽  
Author(s):  
Yi Li ◽  
Jian Zhou ◽  
Runjie Li ◽  
Qingyu Zhang
Keyword(s):  
Molecular Dynamics ◽  
Dynamics Simulation ◽  
Pinning Force ◽  
Theoretical Studies ◽  
Constant Energy ◽  
Zener Pinning ◽  
Interaction Processes ◽  
Interface Characteristics ◽  
Theoretical Predictions ◽  
Ag Particle

Zener pinning between a curved Cu grain boundary (GB) and a differently shaped and oriented Ag particle has been simulated via molecular dynamics. The computed magnitudes of the maximum pinning force agreed with theoretical predictions only when the force was small. As the force increased, discrepancy became obvious. Through careful inspection of the structures of the Cu–Ag interfaces, detailed interaction processes, and variation of the Cu GB during the interaction, the discrepancy is found to correlate with GB faceting, which very likely reduces the maximum pinning force and facilitates boundary passage. GB anisotropy and/or interface characteristics are also found to slightly contribute to the discrepancy. These findings suggest that the assumption of an isotropic GB with constant energy utilized in previous theoretical studies for deriving the maximum pinning force might be inappropriate and that an accurate maximum pinning force could not be predicted without knowing the effects of GB evolution together with detailed properties of both GBs and interfaces.

scholarly journals Solidified Fillings of Nanopores

2005 ◽  
Vol 876 ◽  
Author(s):  
Patrick Huber ◽  
Klaus Knorr
Keyword(s):  
Pore Diameter ◽  
Stacking Faults ◽  
Pore Geometry ◽  
X Ray Diffraction ◽  
X Ray ◽  
Medium Length ◽  
Close Packed Structure ◽  
Packed Structure ◽  
Diffraction Patterns ◽  
Selection Of

AbstractWe present a selection of x-ray diffraction patterns of spherical (He, Ar), dumbbell- (N2, CO), and chain-like molecules (n-C9H20, n-C19H40) solidified in nanopores of silica glass (mean pore diameter 7nm). These patterns allow us to demonstrate how key principles governing crystallization have to be adapted in order to accomplish solidification in restricted geometries. 4He, Ar, and the spherical close packed phases of CO and N2 adjust to the pore geometry by introducing a sizeable amount of stacking faults. For the pore solidified, medium-length chainlike n-C19H40 we observe a close packed structure without lamellar ordering, whereas for the short-chain C9H20 the layering principle survives, albeit in a modified fashion compared to the bulk phase.

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