Lattice-dynamical calculations for orthorhombic sulfur: a non-rigid molecular model
1984; Elsevier BV; Volume: 108; Issue: 6 Linguagem: Inglês
10.1016/0009-2614(84)85059-9
ISSN1873-4448
AutoresC. M. Gramaccioli, Gluseppe Filippini,
Tópico(s)Thermal and Kinetic Analysis
ResumoA lattice-dynamical calculation for orthorhombic (“α”) sulfur has been carried out with a non-rigid molecular model. A difference is observed for the lowest frequencies between the free and the packed molecule. For this reason the empirical force fields which have been fitted to the crystal should be modified, especially by lowering the torsional constants. If such a modified field is used, excellent agreement of calculated thermodynamic functions and crystallographic temperature factors with experimental data is obtained. An underestimation of nearly 2 cal mol−1 K−1 in the values which are currently reported for the entropy of the vapour at room temperature is also inferred.
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