683,381 research outputs found
Generalized Wannier functions: a comparison of molecular electric dipole polarizabilities
Localized Wannier functions provide an efficient and intuitive means by which
to compute dielectric properties from first principles. They are most commonly
constructed in a post-processing step, following total-energy minimization.
Nonorthogonal generalized Wannier functions (NGWFs) [Skylaris et al., Phys.
Rev. B 66, 035119 11 (2002); Skylaris et al., J. Chem. Phys. 122, 084119
(2005)] may also be optimized in situ, in the process of solving for the
ground-state density. We explore the relationship between NGWFs and
orthonormal, maximally localized Wannier functions (MLWFs) [Marzari and
Vanderbilt, Phys. Rev. B 56, 12847 (1997); Souza, Marzari, and Vanderbilt,
ibid. 65, 035109 (2001)], demonstrating that NGWFs may be used to compute
electric dipole polarizabilities efficiently, with no necessity for
post-processing optimization, and with an accuracy comparable to MLWFs.Comment: 5 pages, 1 figure. This version matches that accepted for Physical
Review B on 4th May 201
Occurrence of Ophiocordyceps myrmicarum on a non-Formicidae insect in integrated crop-livestock farming systems.
Na publicação: Fabricia Z. V. Torres; Daniela A. Souza; Marcos Faria; Edison Sujii; Rogerio B. Lopes
Anais...
bitstream/item/63448/1/Anais-XCBVE.pdfEditado por Mauro Celso Zanus, Olga Laureano, George W. B. de Mello e Sandra de Souza Sebben
Polarization fluctuations in insulators and metals: New and old theories merge
The ground-state fluctuation of polarization P is finite in insulators and
divergent in metals, owing to the SWM sum rule [I. Souza, T. Wilkens, and R. M.
Martin, Phys. Rev. B 62, 1666 (2000)]. This is a virtue of periodic (i.e.
transverse) BCs. I show that within any other boundary conditions the P
fluctuation is finite even in metals, and a generalized sum rule applies. The
boundary-condition dependence is a pure correlation effect, not present at the
independent-particle level. In the longitudinal case div P = -rho, and one
equivalently addresses charge fluctuations: the generalized sum rule reduces
then to a well known result of many-body theory.Comment: 4 pages, no figur
Symmetry-adapted Wannier functions in the maximal localization procedure
A procedure to construct symmetry-adapted Wannier functions in the framework
of the maximally-localized Wannier function approach[Marzari and Vanderbilt,
Phys. Rev. B \textbf{56}, 12847 (1997); Souza, Marzari, and Vanderbilt,
\textit{ibid.} \textbf{65}, 035109 (2001)] is presented. In this scheme the
minimization of the spread functional of the Wannier functions is performed
with constraints that are derived from symmetry properties of the specified set
of the Wannier functions and the Bloch functions used to construct them,
therefore one can obtain a solution that does not necessarily yield the global
minimum of the spread functional. As a test of this approach, results of
atom-centered Wannier functions for GaAs and Cu are presented.Comment: 9 pages, 3 figures Submitted to Phys. Rev.
DIÁLOGO ABERTO COM VERA MENEZES DE OLIVEIRA E PAIVA
Entrevistadores:
Patrick Gomes Peixoto
Danilo Pinheiro Lessa AlvesEnira Roberth Maia
Lara Maria dos Santos Pires
Jéssica Caroline Souza Aguiar
Rodrigo B. de Sousa
Danilo Sobral de Souza
Pollyana Gomes Cardoso
Jackson Souza Costa
Leilian França dos Santos
Patrícia Gomes Peixoto
Lucas Maciel de Albuquerqu
Band selection and disentanglement using maximally-localized Wannier functions: the cases of Co impurities in bulk copper and the Cu (111) surface
We have adapted the maximally-localized Wannier function approach of [I.
Souza, N. Marzari and D. Vanderbilt, Phys. Rev. B 65, 035109 (2002)] to the
density functional theory based Siesta method [J. M. Soler et al., J. Phys.:
Cond. Mat. 14, 2745 (2002)] and applied it to the study of Co substitutional
impurities in bulk copper as well as to the Cu (111) surface. In the Co
impurity case, we have reduced the problem to the Co d-electrons and the Cu
sp-band, permitting us to obtain an Anderson-like Hamiltonian from well defined
density functional parameters in a fully orthonormal basis set. In order to
test the quality of the Wannier approach to surfaces, we have studied the
electronic structure of the Cu (111) surface by again transforming the density
functional problem into the Wannier representation. An excellent description of
the Shockley surface state is attained, permitting us to be confident in the
application of this method to future studies of magnetic adsorbates in the
presence of an extended surface state
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