Figure 1

(Color online) Crystal structure of arsenic with rhombohedral $A7$ structure represented by four distorted simple cubic (SC) lattices. The equilibrium bond lengths up to the 14th nearest neighbor can be identified as follows. The first nearest neighbor (1NN) is connected by the heavy solid lines and 2NN by the thin (blue) lines. 3NN, with its length equal to the lattice parameter $a$ in hexagonal setting, is between the atoms 0-2, 0-7, 0-13, and 6-11, etc.; 4NN: 0-4, 0-6, 0-8, and 0-11; 5NN: 3-13, 7-12, 8-18, and 9-21; 6NN: 0-5, 3-8, and 14-23; 7NN: 0-1, 0-20, 3-11, and 4-12; 8NN: 0-15, 3-18, 9-12, and 11-13; 9NN: 0-17, 4-9, and 6-14; 10NN: 1-21, 3-19, 9-15, and 10-13; 11NN: 1-13, 10-21, and 5-13; 12NN: 7-18; 13NN: 9-20 and 2-13; and 14NN: 7-11 and 16-18. Note that the length of $(6\mathrm{NN}+9\mathrm{NN})$ equals the lattice parameter $c$, e.g., the in lines 5-0-17 and 6-14-23.Reuse & Permissions

Figure 2

(Color online) Comparison of force constants and phonon dispersions of arsenic between the $A7$ (top panels) and SC structure (bottom panels, the folded dispersions of two atoms per unit cell are shown along the same directions as in the $A7$ structure). The symbols show the measurements (Ref. 6). The 8NN in the $A7$ structure corresponds to the 4NN in the SC structure.Reuse & Permissions

Figure 3

(Color online) Fermi surface of arsenic with the SC structure. The right panel shows the (110) slice, i.e., the $\Gamma$-R-M-X plane. The nested features of the Fermi surface are clearly shown along the $\Gamma$-R direction with the length of wave vector of $\sim 2k_F$.Reuse & Permissions

Figure 4

(Color online) Calculated force constants and bond lengths of arsenic with the $A7$ and SC structures up to the 14th nearest neighbor as a function of volume.Reuse & Permissions

Figure 5

(Color online) Calculated phonon dispersions of the $A7$ arsenic from $\Gamma$ to T direction under different volumes.Reuse & Permissions