Comment on “Ultrafast terahertz-field-driven ionic response in ferroelectric $\mathrm{BaTi}{\mathrm{O}}_3$”

In Chen et al. [Chen et al., Phys. Rev. B 94, 180104(R) (2016)], an observed increase in x-ray diffraction intensity from $\mathrm{BaTi}{\mathrm{O}}_3$ after an ultrafast terahertz pulse is attributed to enhanced vibrations of the Ti atoms based on a simplified diffraction model. We show that standard Debye-Waller theory leads to more appropriate modeling of time-resolved diffraction intensities, at least in the absence of a fully coherent vibrational response.