**Superconducting I43m CSH_{7} Model Applied to Resistive Transition Temperature Data for Compressed C-S-H at High Pressure**, Dale R. Harshman and Anthony T. Fiory [arXiv_2]

This article updates version 1 by restricting consideration to only the resistive data and excluding the questioned 287.7-K datum reported for carbonaceous sulfur hydride in Snider et al., Nature **585**, 373 (2020). The superconducting transitions are considered in terms of the theoretically-discovered compressed *I*43*m* CSH_{7} structure of Sun et al., Phys. Rev. B **101**, 174102 (2020), which comprises a sublattice similar to *Im*3*m* H_{3}S with CH_{4} intercalates. Positing an electronic genesis of the superconductivity, a model is presented in analogy with earlier work on superconductivity in *Im*3*m* H_{3}S, in which pairing is induced via purely electronic Coulomb interactions across the mean distance ζ between the S and H_{4} tetrahedra enclosing C. Theoretical superconducting transition temperatures for *I*43*m* CSH_{7} are derived as *T*_{C0} = (2/3)^{1/2}σ^{1/2}β/*a*ζ, where β = 1247.4 Å^{2}K is a universal constant, σ is the participating charge fraction, and *a* is the lattice parameter. Analysis suggests persistent bulk superconductivity with a pressure-dependent σ, increasing from σ = 3.5, determined previously for *Im*3*m* H_{3}S, to σ = 7.5 at high pressure owing to additionally participating C-H bond electrons. With an and ζ determined by theoretical structure, calculations of *T*_{C0} at the highest pressures, 258 and 271 GPa, are in agreement with resistive transitions to within an overall uncertainty of ± 3.5 K.

Dale R. Harshman and Anthony T. Fiory, arXiv:2201.01860v2 [cond-mat.supr-con] (2023).