[en] With the purpose of improving the convergence in the method of hyperspherical functions, we introduce pair correlation operators. This makes it possible to perform calculations with rigid NN-potentials where a direct variational calculation would be practically impossible. We obtain a set of nonlinear differential equations for the radial parts of the pair correlation operators. The new approach is used to compute the ground state of the ⁴He nucleus for several realistic NN potentials. The results can be used to estimate the contribution of the potential harmonics in the hyperspherical function method to the binding energy of the nucleus