I reading book, part about gravity. It is Landau-Lifschiz, "Theory of field". And I trying to understand how to calculate cosmological constant. Re-read part with introduction of cosmological constant several times, still not understood. Let's imagine function of space curvature, without presence of mass, is known. In such case it is easy to calculate Cristoffel symbols, Richi tensor etc. But how to find value of cosmological constant from them? I have impression what cosmological constant = 1/(R1*R2), where R1 and R2 are main radiuses of curvature. Is it correct?