Normal Coordinate Analysis and Mean Amplitudes of Vibration of Octasulphur.

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

“…Molecular force field 3.3.1, Adjustment of force constants, The harmonic intramolecular force constant tensor applied in the present work originates from the work of Scott et al [23], who fitted a six-constant potential function of a modified Urey-Bradley force field to the observed intramolecular vibrational frequencies. Cyvin [24] applied these results to calculation of a 18 x 18 symmetry force constant tensor and adjusted the force constants to fit exactly to the observed frequencies. This tensor was then transformed to the Cartesian displacement coordinate system of the molecule thus introducing six zero eigenvalues, which correspond to the three rigid translation and three rigid rotation eigenvectors.…”