The existence of large nonlinear optical coefficients is one of the preconditions for using nonlinear optical materials in nonlinear optical devices. For a crystal. such large coefficients can be achieved by matching photon energies with resonant energies between different bands. and so the details of the crystal band structure play an important role. https://www.getpureroutine.com/quick-grab-blackmores-ache-relief-focus-60-tablets-supply-hot-grab/