Vibrational analysis from linear response theory
Chemical Physics Letters, 345(1-2):179-182
Francesco Filippone and Michele Parrinello (2001)
We present a density functional theory (DFT)-based ab initio method for calculating selected portions of the vibrational spectrum, circumventing the need to evaluate the full Hessian. Our method is based on a combination of variational density functional perturbation theory and the Lanczos diagonalization method. The method is best suited to evaluating the extremal portion of the vibrational spectrum, but it can be adapted to target preselected regions of the spectrum. 1 Present address: Centro Svizzero di Calcolo Scientifico (CSCS), ETH Zurich, via Cantonale, Galleria 2, CH-6928 Manno, Switzerland. Corresponding author. Present address: CNR Istituto di Chimica dei Materiali, v. Salaria km 29,500, C.P. 10, I-00016 Monterotondo Stazione, Italy. Fax: 39-06-9067-2316; email: email@example.com
A New ab-Initio Approach for NMR Chemical Shifts in Periodic Systems
The Journal of Physical Chemistry A, 105(10):1951–1958.
Daniel Sebastiani and Michele Parrinello (2001)
We present a new method for computing NMR chemical shifts and magnetic susceptibilities in extended systems through an ab initio density functional perturbation theory approach. The method is applicable to crystalline and amorphous insulators under periodic boundary conditions, as well as to isolated molecules. The formalism exploits the exponentially decaying nature of localized Wannier orbitals. We have implemented the method in the context of a plane wave pseudopotential approach. The results are in good agreement with experiment and with calculations that use other theoretical methods.
Generalized variational density functional perturbation theory
The Journal of Chemical Physics, 113(17):7102-7109.
Anna Putrino, Daniel Sebastiani, and Michele Parrinello (2000)
We present an implementation of variational perturbation theory in the framework of density functional theory. We use an ab initio pseudopotential scheme with a plane wave basis set and expand the energy functional up to second order in the perturbation. The approach is fairly general and does not rely on the representativeness of the perturbation through a Hamiltonian operator and does not require the use of canonical orbitals. Instead, a functional formulation is used to characterize the perturbation. Several types of applications are presented which illustrate the variety of linear response phenomena that can be treated with our method (vibrational modes, Raman scattering, and nuclear magnetic resonance chemical shift computations). In combination with advanced gradient correction formulas, an accurate description of second order effects in periodic and isolated systems can be achieved.