Precise approximation of the cold pressure curves in quantum-statistical atomic model

Precise approximations were being built in a wide range of volumes for the cold pressure curves in the quantum-statistical atomic model. Different least-square approximations were used: Chebyshev polynomials, the double period method and specially selected basic functions that accounted the asymptotic expansions of quantum-statistical model. The double period method occurs more effective than Chebyshev polynomials for the considered problem. The proposed formulas achieved precision from 0.01% to 0.1%. They are recommended as referenced data.