Chemistry Reference
In-Depth Information
1.2
(b)
1
0.8
0.6
O(PVP) to H(COOH, drug)
distance
O(PVP) to F1(drug) distance
0.4
0.2
0
0
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
r
(Å)
Figure 4.18.
(a) View of a 40.13Å
3
amorphous cell calculated for an amorphous dispersion of
60% (w/w) 6-(2-(5-chloro-2-(2,4-di
uorobenyzloxy)phenyl)cyclopent-1-enyl)picolinic acid in PVP.
The drug is highlighted as a bright wireframe (and also appears in orange color in the online
version) to distinguish it from the polymer. The structurewas obtained after simulation using the
NVE
and
NPT
ensembles with the Dreiding force
field to equilibrate energy and density. A cell of
this type can be subjected to additional simulation to predict properties such as heat capacity
and also provide distributions of structural parameters such as interatomic distances and PDFs.
(b) An additional 200 ps
NVT
calculation with a 1.0 fs time step was performed to obtain 2000
frames, from which the PDFs shown were calculated. The PDFs are shown for two selected
interatomic distances (see the text). Calculations were performed using the Amorphous Cell and
Forcite software packages in Materials Studio version 6.0 (Accelrys, San Diego, CA, USA).
