Table 4. A comparison of the unit-cell parameters of α-ammonium carbamate from the DFT athermal zero-pressure relaxation using CASTEP, from an X-ray single-crystal diffraction (SXD) experiment at room temperature (Adams & Small, 1973 ▸) and from a powder X-ray diffraction experiment (PXRD) at room temperature (Baisch et al., 2006 ▸).
| Formula | (NH4)+·(NH2CO2)− | ||||
| Crystal system | Orthorhombic | ||||
| Space group | Pbca | ||||
| Z | 8 | ||||
| Reference | This work | This work | This work | Adams & Small (1973 ▸) | Baisch et al. (2006 ▸) |
| Method | DFT | Neutron | Neutron | X-ray | X-ray |
| T (K) | Athermal | 4.2 | 180 | 295 | 293 (2) |
| a axis (Å) | 17.0796 | 17.0519 (2) | 17.0908 (2) | 17.121 (6) | 17.119 (4) |
| b axis (Å) | 6.61022 | 6.43518 (7) | 6.48215 (8) | 6.531 (2) | 6.535 (2) |
| c axis (Å) | 6.58788 | 6.68093 (8) | 6.7040 (1) | 6.742 (3) | 6.754 (2) |
| Volume (Å3) | 743.772 | 733.122 (9) | 742.71 (1) | 753.9 (5) | 755.73 (3) |