Chemistry Reference
In-Depth Information
collected at the same temperature. Similar results were obtained for other struc-
tures, indicating that the adequate modeling of the density (
L
4) can indeed help
assign reasonable ADPs to the H-atom sites [
59
]. We also note that the all-
parameter refinement of the U-SPA model brings no significant improvement in
the quality of the fit or the static ED.
The analysis of experimental data of
heptasulfur imide
(Fig.
4d
) leads to even
more drastic differences between the theoretical (MP2/cc-pvtz) U-SPA and the
fitted HC-PA model densities. Figure
4a, b
depicting the residual Fourier maps
obtained by the two methods and the direct-space static difference map (Fig.
4c
)
in the N-S-S plane of the molecule clearly demonstrates that the two markedly
different models exhibit equal statistical consistency with the same data.
¼
Fig. 4 Experimental Fourier (a, b) and direct-space difference (
r
C
-r
HC-PA
) maps (c) in the
N-S-S plane for the
heptasulfur imide
molecule (d). (a) HC-PA refinement; (b) ADP-only
refinement based on the MP2/cc-pVTZ U-SPAs at the same geometry.
Contour lines
are drawn
at 0.05 e
˚
3
.
Solid
,
dashed
, and
dotted lines
are positive, zero, and negative, respectively
