Table 1. Comparison of the Optimized 4,4′-MDI Unit Cell Parameters Based on Different Force Fields.
| parameter | a (Å) | b (Å) | c (Å) | α (°) | β (°) | γ (°) | total relative error (%) |
|---|---|---|---|---|---|---|---|
| experiment29 | 9.974(2) | 8.331(2) | 15.199(3) | 90.000 | 92.250(2) | 90.000 | |
| COMPASS | 9.581 | 8.162 | 16.080 | 90.000 | 94.680 | 90.000 | 14 |
| UNIVERSAL | 10.736 | 8.263 | 14.385 | 90.000 | 84.432 | 90.000 | 22 |
| DREDING | 10.911 | 8.383 | 14.400 | 90.000 | 84.166 | 90.000 | 24 |