Intermolecular interactions and the nature of orientational ordering in the solid fullerenes C 60 and C 70

1992 ◽  
Vol 341 (1661) ◽  
pp. 327-336 ◽  
Keyword(s):  
Molecular Dynamics ◽  
Low Temperature ◽  
Low Pressure ◽  
Intermolecular Potential ◽  
Temperature Phase ◽  
Temperature Structure ◽  
Rotator Phase ◽  
Wide Range ◽  
Orientational Ordering ◽  
Ordering Transition

We have proposed an intermolecular potential for C 60 molecules that not only reproduces the correct low-temperature structure, but also correlates a wide range of experimental properties, including the molecular reorientational time in the room-temperature rotator phase, the volume change at the orientational ordering transition, and the librational frequencies in the low-temperature phase. The low- pressure phases in solid C 70 have been explored using constant-pressure molecular dynamics and an intermolecular potential derived from one that gives an excellent account of the properties of solid C 60 . The molecular dynamics calculations predict three low-pressure phases: a high-temperature rotator phase, a partly ordered phase with trigonal symmetry, and an ordered monoclinic phase. The calculations on C 70 were carried out on a cluster of IBM RS/6000s, operating in parallel.

The low temperature structure of ethylene monolayers physisorbed on the graphite basal plane

1988 ◽  
Vol 66 (4) ◽  
pp. 774-778 ◽  
Author(s):  
Michael A. Moller ◽  
Michael L. Klein
Keyword(s):  
Molecular Dynamics ◽  
Low Temperature ◽  
Basal Plane ◽  
Unit Cell ◽  
Graphite Surface ◽  
Intermolecular Potential ◽  
Temperature Structure ◽  
Low Density ◽  
Molecular Dynamics Calculations ◽  
Graphite Basal Plane

The low temperature structure of low density ethylene monolayers physisorbed on the graphite basal plane has been examined by molecular dynamics calculations with an intermolecular potential based on atom–atom interactions. The simulations predict that the ethylene molecules are arranged in a herringbone with a centered rectangular unit cell of dimensions 4.95 Å × 7.05 Å. In this structure, the molecular C=C axes are parallel to the surface, and are oriented at 60° angles from each other, while the molecular planes are tilted some 55° from the plane of the surface. The structure was found to be essentially independent of the assumed corrugation of the graphite surface.

Single-Crystal X-Ray Scattering Study of Superstructures and Phase Transitions in Graphite-Hno3 and Graphite-Br2 Intercalation Compounds

1982 ◽  
Vol 20 ◽  
Author(s):  
R. Moret ◽  
R. Comes ◽  
G. Furdin ◽  
H. Fuzellier ◽  
F. Rousseaux
Keyword(s):  
Phase Transitions ◽  
Low Temperature ◽  
Room Temperature ◽  
Temperature Phase ◽  
Temperature Structure ◽  
X Ray ◽  
X Ray Scattering ◽  
Scattering Study ◽  
Temperature Liquid ◽  
Low Temperature Phase

ABSTRACTIn α-C5n-HNO3 the condensation of the room-temperature liquid-like diffuse ring associated with the disorder-order transition around 250 K is studied and the low-temperature. superstructure is examined.It is found that β-C8n-HNO3 exhibits an in-plane incommensurate order at room temperature.Two types of graphite-Br2 are found. Low-temperature phase transitions in C8Br are observed at T1 ≍ 277 K and T2 ≍ 297 K. The room-temperature structure of C14Br is reexamined. Special attention is given to diffuse scattering and incommensurability.

The role of hydrogen bonds in order-disorder transition of a new incommensurate low temperature phase β-[Zn-(C7H4NO4)2]·3H2O

2018 ◽  
Vol 233 (1) ◽  
pp. 17-25 ◽  
Author(s):  
Masoumeh Tabatabaee ◽  
Morgane Poupon ◽  
Václav Eigner ◽  
Přemysl Vaněk ◽  
Michal Dušek
Keyword(s):  
Low Temperature ◽  
Hydrogen Bonds ◽  
Dicarboxylic Acid ◽  
Room Temperature ◽  
Temperature Phase ◽  
Temperature Structure ◽  
Modulated Structure ◽  
Q Vector ◽  
Low Temperature Phase

AbstractThe room temperature structure withP21/csymmetry of the zinc(II) complex of pyridine-2,6-dicarboxylic acid was published by Okabe and Oya (N. Okabe, N. Oya, Copper(II) and zinc(II) complexes of pyridine-2,6-dicarboxylic acid.Acta Crystallogr. C.2000,56, 305). Here we report crystal structure of the low temperature phaseβ-[Zn(pydcH)2]·3H2O, pydc=C7H3NO4, resulting from the phase transition around 200K. The diffraction pattern of the low temperature phase revealed satellite reflections, which could be indexed with q-vector 0.4051(10)b* corresponding to (3+1)Dincommensurately modulated structure. The modulated structure was solved in the superspace groupX21/c(0b0)s0, whereXstands for a non-standard centring vector (½, 0, 0, ½), and compared with the room temperature phase. It is shown that hydrogen bonds are the main driving force of modulation.

Superprotonic high temperature phase and refinement of the low temperature structure of CsHSeO4

2001 ◽  
Vol 216 (3) ◽  
Author(s):  
M. A. Zakharov ◽  
Sergej I. Troyanov ◽  
Erhard Kemnitz
Keyword(s):  
Crystal Structure ◽  
High Temperature ◽  
Low Temperature ◽  
High Temperature Phase ◽  
Temperature Phase ◽  
Temperature Structure ◽  
Superprotonic Phase

AbstractThe crystal structure of the high temperature superprotonic phase of CsHSeO

Predicted crystal structures of tetramethylsilane and tetramethylgermane and an experimental low-temperature structure of tetramethylsilane

2010 ◽  
Vol 66 (2) ◽  
pp. 229-236 ◽  
Author(s):  
Alexandra K. Wolf ◽  
Jürgen Glinnemann ◽  
Lothar Fink ◽  
Edith Alig ◽  
Michael Bolte ◽  
...  
Keyword(s):  
Crystal Structure ◽  
Low Temperature ◽  
Crystal Structures ◽  
Ambient Pressure ◽  
Lattice Energy ◽  
Energy Structure ◽  
Temperature Phase ◽  
Temperature Structure ◽  
Field Methods ◽  
Experimental Crystal

No crystal structure at ambient pressure is known for tetramethylsilane, Si(CH3)4, which is used as a standard in NMR spectroscopy. Possible crystal structures were predicted by global lattice-energy minimizations using force-field methods. The lowest-energy structure corresponds to the high-pressure room-temperature phase (Pa\overline{3}, Z = 8). Low-temperature crystallization at 100 K resulted in a single crystal, and its crystal structure has been determined. The structure corresponds to the predicted structure with the second lowest energy rank. In X-ray powder analyses this is the only observed phase between 80 and 159 K. For tetramethylgermane, Ge(CH_3)_4, no experimental crystal structure is known. Global lattice-energy minimizations resulted in 47 possible crystal structures within an energy range of 5 kJ mol−1. The lowest-energy structure was found in Pa\overline{3}, Z = 8.

scholarly journals Achirality in the low temperature structure and lattice modes of tris(acetylacetonate)iron(iii)

2016 ◽  
Vol 45 (19) ◽  
pp. 8278-8283
Author(s):  
Thomas K. Ellis ◽  
Gordon J. Kearley ◽  
Ross O. Piltz ◽  
Upali A. Jayasooriya ◽  
John A. Stride
Keyword(s):  
Molecular Dynamics ◽  
Low Temperature ◽  
Neutron Scattering ◽  
Coordination Complex ◽  
Temperature Structure ◽  
Space Group ◽  
Flexible Ligand ◽  
Ligand Shell ◽  
Lattice Modes

The relatively ubiquitous mononuclear inorganic coordination complex tris(acetylaceonate) iron(iii) has been studied using neutron scattering techniques. The molecular dynamics are shown to be dominated by motions of the highly flexible ligand shell in a non-chiral space group.

A study of the low-temperature structure of SF6

1992 ◽  
Vol 202 (3-4) ◽  
Author(s):  
Lu Hua ◽  
G. Stuart Pawley
Keyword(s):  
Molecular Dynamics ◽  
Low Temperature ◽  
Molecular Dynamics Method ◽  
Temperature Structure ◽  
Array Processor ◽  
Distributed Array ◽  
Dynamics Method

AbstractThe stress-free molecular dynamics method has been carried out on a Distributed Array Processor (DAP) to study the phases of SF

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