Table 1 Electronic, vibrational, and superconducting properties of dynamically stable phases at 270 GPa.

Structure	Θ_D	N_F	\({\omega }_{\ln }\)	λ	\({T}_{{{{\rm{c}}}}}^{{{{\rm{ME}}}}}\)	\({T}_{{{{\rm{c}}}}}^{{{{\rm{AD}}}}}\)	P_stab
\(Im\bar{3}m\) H₃S	1288	0.050	1626	1.24	175–162	166–148	N/A
R3m H₃S	1330	0.044	1652	1.02	135–115	125–107	N/A
\(Im\bar{3}m\) O_h-CS₇H₂₄	1366	0.030					260–270
\(Pm\bar{3}m\) O_h-CS₁₅H₄₈	1382	0.040					255–270
\(Pm\bar{3}m\) O_h-CS₅₃H₁₆₂	1368	0.048					200–270
Amm2 T_d-CS₃H₁₂	1752	0.028	1370	0.85	80–67	76–63	160–270
Amm2 T_d-CS₇H₂₄	1824	0.039					250–270
Fmm2 T_d-CS₇H₂₄	1525	0.039					200–270
Pm T_d-CS₇H₂₄	1701	0.033					140–270
Amm2 T_d-CS₁₅H₄₈	1623	0.033					180–270
Amm2 T_d-CS₅₃H₁₆₂	1678	0.046					200–270
Cmcm CSH₇	1821	0.026					140–270
R3m CSH₇	1780	0.028	1703	1.10	156–140	147–129	140–270
Cm CS₃H₁₃	1810	0.025	1704	1.01	142–121	128–110	140–270
R3m CS₃H₁₃	1664	0.028	1250	1.02	111–98	96–83	140–270
Cm CS₇H₂₅	1832	0.031	1551	0.94	115–100	104–88	140–270
R3m CS₇H₂₅	1729	0.038					160–270
R3m CS₁₅H₄₉	1760	0.034					140–270
R3m CS₅₃H₁₆₃	1792	0.043					200–270

Debye temperature (Θ_D, in K), density of states at the Fermi level (N_F, in states eV⁻¹ A⁻³), logarithmic average of phonon frequencies (\({\omega }_{\ln }\), in K), electron–phonon coupling constant (λ), and superconducting critical temperature (T_c, in K) obtained via numerical solution of the Migdal–Eliashberg equations (ME) and the Allen–Dynes equation for strongly coupled systems (AD) using μ^* = 0.1−0.13 at 270 GPa. The pressure range where dynamic stability was confirmed in this study (phonon calculations were carried out between 140 and 270 GPa, see Section S2.4, S3.4, and S4.4) is also provided in GPa.
Calculated strong coupling and shape dependence correction factors, f₁ and f₂, used in the AD equation are: \(Im\bar{3}m\) H₃S: f₁ = 1.067, f₂ = 1.022, R3m H₃S: f₁ = 1.052, f₂ = 1.017, T_d-CS₃H₁₂: f₁ = 1.039, f₂ = 1.016, R3m CSH₇: f₁ = 1.058, f₂ = 1.022, Cm CS₃H₁₃: f₁ = 1.046, f₂ = 1.013, R3m CS₃H₁₃: f₁ = 1.047, f₂ = 1.019, Cm CS₇H₂₅: f₁ = 1.047, f₂ = 1.017.

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