High transition temperature superconductivity originates from the Coulombic interaction between two adjacent charge reservoirs (hole and electron). The optimal transition temperature is given by the algebraic expression:
TC0 = kB−1 β (ση/A)1/2 ζ−1
where ζ is the interaction distance (along the transverse axis), σ/A is the areal charge density per type I layer per formula unit for participating charges, η is the number of mediating layers (e.g., the number of cuprate planes), and β (= 0.1075 ± 0.0003 eV Å2) is a universal constant; e–2β is approximately twice the reduced electron Compton wavelength. The relevant experimental parameters and the calculated values of TC0 are listed under Tabulated results for 50 optimal high-TC materials from seven superconductor families.