. 2019 May 8;6(Pt 4):558–571. doi: 10.1107/S2052252519003014

Table 2. Estimates of acoustic mode frequencies from supercell calculations, from mta-NoMoRe and TLS analysis.

Standard uncertainties for AO and FG models are less than 1%.

	Y	W
Supercell calculations (cm⁻¹)	25, 33, 37	21, 25, 28
AO model (cm⁻¹)	28, 33, 33	23, 25, 30
FG model (cm⁻¹)	64, 34, 35	24, 25, 30
TLS analysis^† (cm⁻¹)	29, 33, 35	30, 32, 37 31, 33, 37

^†

For W there are two molecules in the asymmetric unit, and TLS analysis was done separately for both of them. The frequencies listed from supercell calculations are the means over the Brillouin zone. While calculating mean values of frequencies over the Brillouin zone for acoustic modes we assume that modes are not degenerated. As both polymorphs crystallize in Inline graphic , all k-points are equally important, thus we just calculate the sum of frequencies from all k-points, and then divide it by number of k-points.