title: Ab initio analytical Raman intensities for periodic systems through a coupled perturbed Hartree-Fock/Kohn-Sham method in an atomic orbital basis. I. Theory.
abstract: We present a fully analytical formulation for calculating Raman intensities of crystalline periodic systems using a local basis set. Numerical differentiation with respect to atomic coordinates and with respect to wavevectors is entirely avoided as is the determination of crystal orbital coefficient derivatives with respect to nuclear displacements. Instead, our method utilizes the orbital energy-weighted density matrix and is based on the self-consistent solution of first- and second-order Coupled Perturbed Hartree-Fock/Kohn-Sham equations for the electronic response to external electric fields at the equilibrium geometry. This method has also been implemented in the Crystal program, which uses a Gaussian type basis set.
authors.affiliation: Dipartimento di Chimica, Università di Torino and NIS-Nanostructured Interfaces and Surfaces-Centre of Excellence, Via P. Giuria 7, 10125 Torino, Italy.
authors.forename: Lorenzo
authors.initials: L
authors.lastname: Maschio
authors.forename: Bernard
authors.initials: B
authors.lastname: Kirtman
authors.forename: Michel
authors.initials: M
authors.lastname: Rérat
authors.forename: Roberto
authors.initials: R
authors.lastname: Orlando
authors.forename: Roberto
authors.initials: R
authors.lastname: Dovesi