The computed polarization of the (R)-OH-QCl is more than three times larger that of the experimentally measured. The discrepancy can have many origins, both 10.0 10.3 8.9 a Ref. b Ref. experimental and computational: Incomplete switching typically cause experimental polarization to fall below the predicted. One cause of incomplete switching is finite electrical conductivity causing the sample to experience a heterogeneity of the electric field. Ferroelectric domain wall motion can also be pinned by point defects, grain boundaries or interfaces during the switching process. Such defects can arise easily because of microstructural properties of polycrystalline materials and specific synthesis conditions. The discrepancy might be related to the use of polycrystalline samples. The presence of defects can also in some samples prevent complete polarization switching . Moreover, DFT calculations do not include temperature effects, such as thermal vibration. As a result, the microscopic dipoles tend to align to a larger degree than they would at room temperature, which causes overestimation of polarization. The predicted lattice constants are also smaller than the experimentally reported, with the largest deviation of 2.58% for the c-axis in the Br-compound. This underestimation can also contribute to an overestimation of the calculated polarization.