Abstract
The neutron scattering cross-section has been measured for low-density sulphur hexafluoride gas. The molecular term gives the S-F distance as 1-573 ±0-008 Å. The intermolecular term is analysed in terms of the structural second virial coefficient [1]. Although a Lennard-Jones (LJ) 12-6 potential fits the second virial coefficient over a wide range of temperature it is clearly inconsistent with our structural data at 20°C. Two intermolecular potentials have been found which fit both the second virial and the structural second virial coefficient data. One is a LJ 28-7 potential, virtually that proposed by Hamann and Lambert [14]. The other is a simple anisotropic site—site potential. The sites are at the fluorine nuclei and have LJ 12-6 potentials between sites with parameters, c/&b /T=61-39 and c/A = 3-024. The site-site potential is preferred on physical grounds. Neither a simple average nor a Boltzmann average of our site-site potential, which are virtually LJ 28-7 and LJ 12-6 respectively, has any apparent connection with the previously proposed LJ potentials. Moreover our proposed site-site potential differs substantially from a previous one [19] which was found suitable for the plastic crystal phase of SF6.
| Original language | English |
|---|---|
| Pages (from-to) | 1089-1108 |
| Number of pages | 20 |
| Journal | Molecular Physics |
| Volume | 50 |
| Issue number | 5 |
| DOIs | |
| Publication status | Published - 1983 |
| Externally published | Yes |
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ASJC Scopus subject areas
- Biophysics
- Molecular Biology
- Physical and Theoretical Chemistry
- Condensed Matter Physics
Cite this
The structural second virial coefficient : II The intermolecular pair-potential for sulphur hexafluoride. / Powles, J. G.; Dore, J. C.; Deraman, Mohamad; Osae, E. K.
In: Molecular Physics, Vol. 50, No. 5, 1983, p. 1089-1108.Research output: Contribution to journal › Article
}
TY - JOUR
T1 - The structural second virial coefficient
T2 - II The intermolecular pair-potential for sulphur hexafluoride
AU - Powles, J. G.
AU - Dore, J. C.
AU - Deraman, Mohamad
AU - Osae, E. K.
PY - 1983
Y1 - 1983
N2 - The neutron scattering cross-section has been measured for low-density sulphur hexafluoride gas. The molecular term gives the S-F distance as 1-573 ±0-008 Å. The intermolecular term is analysed in terms of the structural second virial coefficient [1]. Although a Lennard-Jones (LJ) 12-6 potential fits the second virial coefficient over a wide range of temperature it is clearly inconsistent with our structural data at 20°C. Two intermolecular potentials have been found which fit both the second virial and the structural second virial coefficient data. One is a LJ 28-7 potential, virtually that proposed by Hamann and Lambert [14]. The other is a simple anisotropic site—site potential. The sites are at the fluorine nuclei and have LJ 12-6 potentials between sites with parameters, c/&b /T=61-39 and c/A = 3-024. The site-site potential is preferred on physical grounds. Neither a simple average nor a Boltzmann average of our site-site potential, which are virtually LJ 28-7 and LJ 12-6 respectively, has any apparent connection with the previously proposed LJ potentials. Moreover our proposed site-site potential differs substantially from a previous one [19] which was found suitable for the plastic crystal phase of SF6.
AB - The neutron scattering cross-section has been measured for low-density sulphur hexafluoride gas. The molecular term gives the S-F distance as 1-573 ±0-008 Å. The intermolecular term is analysed in terms of the structural second virial coefficient [1]. Although a Lennard-Jones (LJ) 12-6 potential fits the second virial coefficient over a wide range of temperature it is clearly inconsistent with our structural data at 20°C. Two intermolecular potentials have been found which fit both the second virial and the structural second virial coefficient data. One is a LJ 28-7 potential, virtually that proposed by Hamann and Lambert [14]. The other is a simple anisotropic site—site potential. The sites are at the fluorine nuclei and have LJ 12-6 potentials between sites with parameters, c/&b /T=61-39 and c/A = 3-024. The site-site potential is preferred on physical grounds. Neither a simple average nor a Boltzmann average of our site-site potential, which are virtually LJ 28-7 and LJ 12-6 respectively, has any apparent connection with the previously proposed LJ potentials. Moreover our proposed site-site potential differs substantially from a previous one [19] which was found suitable for the plastic crystal phase of SF6.
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U2 - 10.1080/00268978300102881
DO - 10.1080/00268978300102881
M3 - Article
VL - 50
SP - 1089
EP - 1108
JO - Molecular Physics
JF - Molecular Physics
SN - 0026-8976
IS - 5
ER -