The correlations of the forces obtained from AIMD and CMD using the best force-field parameters are displayed along with the score metrics (R 2 and root-mean-squared error, RMSE) in Fig. . The deviations of the energy and stress are also shown in Fig. The lattice constant and density of a molecular crystal are good indicators to check the accuracy of nonbonded interactions in condensed matter. We compared experimentally measured lattice constants with the results derived from the static DFT-based structural optimizations (PBE and DFT-D3) and the equilibrium structure from CMD at 153 K with all degrees of freedom for cell lengths and angles. The mean Ho-ow (ow) and Ho-o1= (o1=) distances were also calculated for the purpose of validation. Table summarizes the experimental X-ray data at 153 K and the structural parameters obtained from ab initio and CMD calculations. It should be noted that the cell dimensions derived from DFT do not account for thermal expansion at a finite temperature. The mean Ho-o1= and Ho-ow distances derived from PBE were slightly longer than those from DFT-D3, which were closer to the X-ray data. However, the effect of the dispersion correction for the Ho-o1= and Hoow distances included in DFT-D3 is negligibly small. Overall, the introduction of dispersion correction had only a small effect of the reproduction of the crystalline structure; therefore, the training data were built from the results of AIMD calculations using the PBE functional.