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Center for Nonlinear Studies |
We report our developments in the efficient evaluation of vibrational characteristics: harmonic frequencies, infrared and Raman intensities within a generalized Kohn–Sham density functional theory using Gaussian orbitals and periodic boundary conditions. The use of an atomic orbital formulation for all computationally challenging steps allows us to adapt the direct space fast multipole method for the Coulomb-type infinite summations. Our implementation also exploits the local character of the exact Hartree-Fock exchange in nonconducting systems. Exchange-correlation contributions are computed using extensive screening and fast numerical quadratures. A discretized form of the Berry phase is used to evaluate a periodic dipole moment and its derivatives with respect to nuclear coordinate displacements which constitute infrared intensities. Performance of several pure and hybrid density functionals is assessed in benchmark calculations for one-, two- and three-dimensional periodic systems.
Host: Svetlana Kilina