Molecular distortion in orthorhombic sulphur; a calculation

Kurittu, J.; Pawley, G. S.

doi:10.1107/s0567739473001580

Cited by 8 publications

(8 citation statements)

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“…2 shows the distortion of the molecule from the ideal mmm symmetry when in a crystal environment. The only distortions that can be found from crystal diffraction methods are those which break the free molecular symmetry but not the molecule crystal-site symmetry (Kurittu & Pawley, 1973). Thus some distortion will be present but undetectable in the coordinates X m of Table 3 and the bond lengths of Fig.…”

Section: Discussionmentioning

confidence: 98%

The structure of anthracene-d10 at 16 K using neutron diffraction

Chaplot¹,

Lehner²,

Pawley³

1982

Acta Crystallogr Sect B

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The crystal structure of anthracene-d~0 at 16 K has been refined using neutron diffraction measurements [Cl4Dlo, P2~/a, a = 8.37 (3), b = 6.00(2), c = 11.12 (4)/k, fl = 125.4 (1) ° ]. Using 1105 structure factors, an R factor of 6.0% was obtained, which reduced to 3.2% when a simple one-parameter correction was made for multiple Bragg scattering, although this correction is not correlated to the crystal structure result. Constrained refinements have also been carried out which indicate significant distortions in the crystalline state from the free-molecule symmetry of mmm.The thermal-parameter analysis shows that the T tensor is reduced most on reducing the temperature from 298 to 16 K, whereas the thermal motion of the D nuclei is hardly affected. A comparison with the room-temperature result confirms the accuracy of the molecular-geometry measurement, and shows a molecular reorientation of over 1 o between 16 and 298 K.

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Section: Discussionmentioning

confidence: 98%

The structure of anthracene-d10 at 16 K using neutron diffraction

Chaplot¹,

Lehner²,

Pawley³

1982

Acta Crystallogr Sect B

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“…Actual calculation of the equilibrium structure is possible by applying a two stage iteration procedure, as follows. First, the lattice parameters ( p } and the molecular position and orientation parameters ( R k j and (6,) are found by a parameter variation method, originally described by Pawley [20] and subsequently applied in many studies [ l l , [15][16][17][18]. This stage completes minimization of the function Q C + p V by retaining the initial configuration of the molecule and is all that is needed for calculations within the rigid molecule approximation.…”

Section: >mentioning

confidence: 99%

“…Physica Scripta 21 In the present work, a deformable molecule model is applied which assumes that the intramolecular atom-atom forces arising from the molecular distortion are harmonic, while 6-exp potential functions are used for the intermolecular forces, as before. A similar model has previously been applied [18] to a calculation of the molecular distortion in orthorhombic sulphur, but, as discussed below, the present calculation differs from the previous one in some important details, such as in the choice of parameters for describing the intermolecular and intramolecular forces. Furthermore, the calculation has now been extended to include the structure of the crystal under hydrostatic pressure and, in the following paper [19] , lattice dynamics.…”

Section: Introductionmentioning

confidence: 99%

Lattice Statics with Deformable Molecules: α-Sulphur Under Hydrostatic Pressure

Kurittu

1980

Phys. Scr.

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“…Some examples are S 6 , γ-S 7 , δ-S 7 , α-S 8 , γ-S 8 , S 10 , S 11 , S 12 , S 13 , α-S 18 , β-S 18 , and S 20 − molecular distortion in the crystal, crystal lattice vibrations, , lattice dynamics, effects of hydrostatic pressure, and molecular dynamics simulation …”

Section: Introductionmentioning

confidence: 99%

Spherical and Aspherical Intermolecular Force Fields for Sulfur Allotropes

Abraha

Williams

1999

Inorg. Chem.

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Elemental sulfur exists in many crystalline forms, with many of these forms being composed of discrete S n cyclic molecules. Eleven experimentally determined S n crystal structures are used to define a new spherical S···S intermolecular force field of the (exp-6) type. Evidence is presented that the bonded sulfur atom in these structures is not spherical. The asphericity was modeled by placing repulsion bumps at optimized locations on the sulfur atoms to represent lone pair electron repulsion. The bump locations deviate from perfect tetrahedral geometry, being located more perpendicular to the S−S−S plane. A new aspherical sulfur intermolecular force field was derived from eleven S n crystal structures. The aspherical force field gives an improved prediction of the S n crystal structures.

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Molecular distortion in orthorhombic sulphur; a calculation

Cited by 8 publications

References 0 publications

The structure of anthracene-d10 at 16 K using neutron diffraction

The structure of anthracene-d10 at 16 K using neutron diffraction

Lattice Statics with Deformable Molecules: α-Sulphur Under Hydrostatic Pressure

Spherical and Aspherical Intermolecular Force Fields for Sulfur Allotropes

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