where Σ R,SWS = hτ 2 diag(. . . , 1 m k , . . .) and k enumerates all the Cartesian coordinates. This representation has two main differences compared to Equation . The first one is that the diagonal elements of matrix Σ R,SWS in Equation are given by the parametrization from Equation , rather than computed from the harmonic potential. The second difference is that all the non-diagonal elements in Σ R,SWS , which carry information on the correlations between different Cartesian coordinates of atoms, are zeros. Both differences appear due to the absence of information about the shape of the local potential of nuclei in the SWS procedure, which makes it physically less justified in comparison to WS. Accordingly, SWS is expected to be less accurate, although it is not yet exactly clear how large will be the accuracy loss in different use scenarios. At the same time SWS gains an advantage, that it does not require a preliminary optimization of molecular structure and calculation of Hessian.