Orthorhombic ScB3 and hexagonal ScB6 with high hardness

Pressure-induced novel structure with graphene-like boron-layer in titanium monoboride

“…In addition, the B atoms form one-dimensional zigzag chain with the identical B-B length of 1.812 Å along b-axis and identical B-B-B angle of 114.89 • . This B-B bond length is comparable to that of α-B (1.669-2.003 Å), [61] γ-B (1.661-1.903 Å), [62] Pnma-ScB 3 and P6 3 mc-ScB 6 , [63] uncovering a strong B-B covalent bond. Hence, the Pnma-TiB phase is composed of the distorted TiB 7 enneahedron and one-dimensional zigzag chain of B atoms.…”

Coexistence of superconductivity and electride states in Ca2H with an antifluorite-type motif under compression

“…To gain steady superconducting calcium-based hydrides with electride characteristics, we conducted structure prediction of the Ca–H system in the Ca-rich region under pressure via the swarm-intelligence structure search method as performed in the CALYPSO code 55,56 with high efficiency, which has been successfully utilized to discover stable or metastable materials. 57–61 The geometry optimizations of structures and the electronic property calculations were performed through the vienna ab initio simulation package (VASP) code. 62 Projector augmented-wave (PAW) 63 pseudopotentials with valence electron configurations of Ca 3s 2 3p 6 4s 2 and H 1s 1 were chosen.…”

High-Tc superconductivity of polyhydride Rb2MgH18 with a layered hydrogen structure at high pressure

“…The structure searches for Rb x Mg y H z ( x = 1–2, y = 1–2, z = 1–4, 6, 8–10, 12, 16, 18, 24, 28) at 100, 200, and 300 GPa were carried out using a particle-swarm optimization algorithm implemented in the CALYPSO software, 45–47 which has been successfully applied to various high-pressure systems. 48–53 Simulated cells containing up to 62 atoms were adopted. The total number of searched structures in this work was around 151 000.…”