scholarly journals On the Structure Factors of Aqueous Mixtures of 1-Propanol and 2-Propanol: X-Ray Diffraction Experiments and Molecular Dynamics Simulations

2018 ◽  
Vol 255 (11) ◽  
pp. 1800215 ◽  
Author(s):  
José G. Méndez-Bermúdez ◽  
Hector Dominguez ◽  
László Temleitner ◽  
László Pusztai
Keyword(s):  
Molecular Dynamics ◽  
Molecular Dynamics Simulations ◽  
Aqueous Mixtures ◽  
X Ray Diffraction ◽  
X Ray ◽  
Structure Factors ◽  
Dynamics Simulations

scholarly journals Crystal structure of Ag-exchanged levyne intergrown with erionite: Single-crystal X-ray diffraction and Molecular Dynamics simulations

2020 ◽  
Vol 105 (11) ◽  
pp. 1631-1638 ◽  
Author(s):  
Georgia Cametti ◽  
Sergey V. Churakov
Keyword(s):  
Molecular Dynamics ◽  
Single Crystal ◽  
Molecular Dynamics Simulations ◽  
Exchange Process ◽  
Structural Refinement ◽  
X Ray Diffraction ◽  
Threefold Axis ◽  
Space Group ◽  
X Ray ◽  
Dynamics Simulations

Abstract The modification of natural zeolites via ion exchange is an efficient technique used to improve their performances and tune their properties for specific applications. In this study, a natural levyne-Ca intergrown with erionite was fully exchanged by Ag+ and its structure [with idealized chemical composition Ag6(Si,Al)18O36·18H2O] was investigated by combining a theoretical and experimental approach. Single-crystal X-ray diffraction data demonstrated that Ag-levyne maintained the R3m space group, characteristic of the natural levyne. Ag ions distribute over partially occupied sites along the threefold axis and, differently from the pristine material, at the wall of the 8-membered ring window of the lev cavity. The lack of ~30% of Ag ions that could not be located by the structural refinement is ascribed to the strong disorder of the extraframework occupants. The structural results obtained by Molecular Dynamics simulations are in overall agreement with the experimental data and showed that, on average, Ag+ is surrounded by ~2 H2O and 1 framework oxygen at distances between 2.43 and 2.6 Å. Molecular Dynamics trajectories indicate that the occurrence of silver inside the D6R cage depends on the water content: silver occupancy of D6R cages is estimated to be 83, 30, and 0% when the structure contains 3, 2.5, and 2 H2O per Ag ion, respectively. The cation-exchange process, as demonstrated by scanning electron microscopy and energy-dispersive spectroscopy (SEM-EDS) spectrometry, affects the intergrown erionite as well. A structural characterization of the Ag-erionite phase (with dimension <100 μm) was possible by means of a CuKα micro-focus source: structure solution pointed to P63/mmc space group, indicating no change with respect to natural erionite. In agreement with previous studies, K ions in the cancrinite cage could not be exchanged, whereas Ag+ is found in the eri cavity.

scholarly journals [UO2(NH3)5]Br2·NH3: synthesis, crystal structure, and speciation in liquid ammonia solution by first-principles molecular dynamics simulations

2015 ◽  
Vol 44 (16) ◽  
pp. 7332-7337 ◽  
Author(s):  
Patrick Woidy ◽  
Michael Bühl ◽  
Florian Kraus
Keyword(s):  
Crystal Structure ◽  
Molecular Dynamics ◽  
Bond Strength ◽  
Molecular Dynamics Simulations ◽  
First Principles ◽  
Liquid Ammonia ◽  
Ammonia Solution ◽  
X Ray Diffraction ◽  
X Ray ◽  
Dynamics Simulations

X-Ray diffraction and Car–Parrinello molecular dynamics simulations furnish insights into the speciation of uranyl(vi) in liquid ammonia, calling special attention to the effect of solvation on the U–N bond length and bond strength.

X-ray Scattering Measurements of the Ag(111) Surface Thermal Expansion

2001 ◽  
Vol 678 ◽  
Author(s):  
Cristian E. Botez ◽  
William C. Elliott ◽  
Paul F. Miceli ◽  
Peter W. Stephens
Keyword(s):  
Molecular Dynamics ◽  
Thermal Expansion ◽  
Molecular Dynamics Simulations ◽  
Temperature Interval ◽  
X Ray Diffraction ◽  
X Ray ◽  
X Ray Scattering ◽  
Scattering Measurements ◽  
The One ◽  
Dynamics Simulations

AbstractWe have used synchrotron X-ray diffraction to study the thermal expansion of the Ag(111) surface. Throughout the temperature interval between 300 and 1100K, we observed that the separation between the first and the second atomic layers at the surface, 12 d, differs from its bulk counterpart, d, by less than 1%, indicating that the thermal expansion at the surface is similar to the one in the bulk. This result represents the first experimental confirmation of the predictions from molecular dynamics simulations, which indicate a small enhancement of the anharmonic effects at this surface.

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