A mixed-space approach to first-principles calculations of phonon frequencies for polar materials.

We propose a mixed-space approach using the accurate force constants calculated by the direct approach in real space and the dipole-dipole interactions calculated by linear response theory in reciprocal space, making the accurate prediction of phonon frequencies for polar materials possible using the direct approach as well as linear response theory. As examples, by using the present approach, we predict the first-principles phonon properties of the polar materials α-Al(2)O(3), MgO, c-SiC, and h-BN, which are in excellent agreement with available experimental data.