Table 1. Structural information for few-layer BP.
| NL | a (Å) | b (Å) | Δc (Å) | R1 (Å) | R2 (Å) | θ1/θ1′ (°) | θ2/θ2′ (°) |
|---|---|---|---|---|---|---|---|
| 1 | 4.58 | 3.32 | 3.20 | 2.28 | 2.24 | 103.51 | 96.00 |
| 2 | 4.52 | 3.33 | 3.20 | 2.28 | 2.24 | 102.96 | 96.21/95.92 |
| 3 | 4.51 | 3.33 | 3.20 | 2.28 | 2.24 | 102.81/102.74 | 96.30/95.99 |
| 4 | 4.50 | 3.34 | 3.20/3.21 | 2.28 | 2.24 | 102.76/102.67 | 96.34/96.01 |
| 5 | 4.49 | 3.34 | 3.20/3.21 | 2.28 | 2.24 | 102.71/102.63 | 96.37/96.05 |
| Bulk | 4.47 | 3.34 | 3.20 | 2.28 | 2.25 | 102.42 | 96.16 |
BP, black phosphorus.
Lattice constants a, b and Δc (the interlayer spacing between two adjacent BP layers) and structural parameters R1, R2, θ1 and θ2 of few-layer and bulk BP calculated using optB88-vdW. There are slight differences in θ1 and θ2 between the outermost and inner layers.