the harmonic approximation gives symmetric probability distribution, as it is obtained from the model symmetric potential. Therefore no anharmonic shifts of the interatomic distance can be observed from the ensemble of structures sampled in this case. Although MD can be used with anharmonic PES, being a classical simulation technique, it cannot recover quantum effects (NQEs). Nevertheless, some successful examples of modified MD describing quantum properties exist in the literature. It is possible to replace the classical vibrational amplitude l = ⟨r 2 ⟩ -⟨r⟩ 2 with its quantum analogue in harmonic approximation. This substitution is justified by the domination of the harmonic potential in the second moment of the interatomic distribution.