Crystal structure evolution and superconductivity of the ternary hydride CSH3 under pressure

Under high-pressure conditions, the changes of atomic arrangement and stacking of the lattice structures lead to enhanced electronic correlation effect and even superconductivity. Motivated by a recent experimental demonstration of pressure-induced superconductivity in a C-S-H system, in this work, we construct a CSH3 system via simple combining of H3S and C to study the crystal structural evolution and possible superconductivity at high pressure using first-principles calculations. We predicted the trigonal and orthorhombic crystal structures of CSH3 under pressure, with the space groups R-3m, Pbcm, and Pmmn, respectively. We find that the trigonal R-3m phase transform to the orthorhombic Pbcm phase at 210 GPa, at which the volume of CSH3 phases drops by similar to 7%. Due to large the electronic density of states of the H component near the Fermi level, the T-c is higher in the Pbcm and the Pmmn phases than in the R-3m phase. A T-c as high as 98 K is found for the Pbcm phase at 250 GPa.