Correlation dependence { ₀} = { ₀} (, , {Z₂}) is established between critical amplitude { ₀} of coefficient isothermal compressibility {Kₓ}, acentric factor ω, critical compressibility factor {Z₂}, and critical index. A description of critical amplitude ₀^{ (e) } of 24 substances is used as an example to show that the correlations of Gerasimov (2003) ; Perkins et al. (2013) ; and Abbaci (2024) in the form { ₀} = { ₀} (), and of Ivanov (2008) in the form { ₀} = { ₀} (), are vastly inferior to the proposed correlation { ₀} = { ₀} (, , {Z₂}) in their accuracy of calculation. Three intervals of the critical index are considered: 1, 1. 242 (interval I), 1. 1, 1. 242 (interval II), and 1. 239, 1. 242 (interval III). In intervals II and III, the dependence of ₀^{ (e) } on is close to linear, so it is described by others that are linear in respect to ω, {Z₂}, and. The dependence of ₀^{ (e) } on is nonlinear in interval I. The correlation for { ₀} has the form ₀^* = {C₀} + {C₁} + {C₂}Z₂^{ - n} + {C₃}{ ^{ - g}}, where g = 9. 1 and n = 2. It is established that in all three considered intervals of, the accuracy of nonlinear correlation ₀^* is superior to the others studied in this work for { ₀}. Deviations of { ₀} from ₀^{ (e) } in, e. g. , interval I for correlations of Gerasimov, Ivanov, Perkins et al. , and Abbaci, and for linear correlations and correlation ₀^* proposed in this work, are estimated using absolute average deviations 22. 1, 8. 5, 16. 5, 21. 6, 6. 6, 5. 5, and 2. 7%, respectively.
Kudryavtseva et al. (Thu,) studied this question.