Table 2. Results of the lattice-energy minimizations on selected models containing two (c′ = 2c 0, Z = 8) and four double layers (c′ = 4c 0, Z = 16).
Further models containing a mixture of L, M, A and B layers (e.g. LMAA) were minimized with force fields only (see Table S3 in supporting information).
| Stacking sequence | Force-field methods | DFT-D | |||
|---|---|---|---|---|---|
| Two double layers | Four double layers | Space group† | Relative energy (kJ mol−1) | Relative energy (kJ mol−1) | Remarks |
| LL | LLLL | P21/a, Z = 4 | 0.00 | 1.03 | α-phase |
| LLLM | P21/a, Z = 16 | 0.02 | 0.46 | ||
| LM | LMLM | C2/c, Z = 8 | 0.05 | 0.00 | β-phase |
| LLMM | A2/a, Z = 16 | 0.02 | 0.46 | ||
| LLLA | P21/a, Z = 16 | 1.03 | 2.11 | ||
| LA | LALA | P21/c, Z = 4 | 2.01 | 4.19 | |
| LLAA | P21/a, Z = 8 | 1.03 | 3.19 | ||
| LLLB | P21/a, Z = 16 | 0.99 | 2.11 | ||
| LB | LBLB | A2/n, Z = 8 | 1.92 | 4.19 | |
| LLBB | A2/a, Z = 16 | 0.99 | 2.67 | ||
| LMAB | P2/a, Z = 8 | 1.01 | 2.61 | ||
| LMAM | P21/a, Z = 16 | 1.01 | 1.73 | ||
| LMBM | P21/a, Z = 16 | 1.05 | 1.71 | ||
†
Space group of the model used for DFT-D.