The paper is structured as follows. First we introduce and compare possible sampling procedures, including our simplified version of Wigner sampling. Then we perform a benchmarking of vibrationally-averaged rotational constants. We demonstrate the proof-of-principle for the approach using the diatomic system of the molecular hydrogen cation. A benchmark set of five small (no more than six atoms) molecules is used to evaluate a method for calculation of rotational constants from MD trajectories. The resulting procedure is applied to another two moderately-sized molecules (20 and 62 atoms). Next, we show the application of the sampling routines for the calculation of vibrational spectra for difluoromethane. Finally, different sampling methods are applied to several systems with known experimental data. All molecules used throughout this work are shown in Figure . 2 Theory