Showing papers by "Paolo Giannozzi published in 2018"
University of Lorraine1, University of Paris2, University of Düsseldorf3, University of Warsaw4, University of Udine5, CentraleSupélec6, University of Western Australia7, University of Bern8, University of Copenhagen9, City University of New York10, Michigan State University11, Monash University12, Bruker13, Lund University14, Vienna University of Technology15, University of Jena16, University of Bremen17
TL;DR: An overview over current research that is related to a broader notion of QCr is given, and options how QCr can evolve to become a complete and independent domain of natural sciences are discussed.
Abstract: Crystallography and quantum mechanics have always been tightly connected because reliable quantum mechanical models are needed to determine crystal structures. Due to this natural synergy, nowadays accurate distributions of electrons in space can be obtained from diffraction and scattering experiments. In the original definition of quantum crystallography (QCr) given by Massa, Karle and Huang, direct extraction of wavefunctions or density matrices from measured intensities of reflections or, conversely, ad hoc quantum mechanical calculations to enhance the accuracy of the crystallographic refinement are implicated. Nevertheless, many other active and emerging research areas involving quantum mechanics and scattering experiments are not covered by the original definition although they enable to observe and explain quantum phenomena as accurately and successfully as the original strategies. Therefore, we give an overview over current research that is related to a broader notion of QCr, and discuss options how QCr can evolve to become a complete and independent domain of natural sciences. The goal of this paper is to initiate discussions around QCr, but not to find a final definition of the field.
104 citations
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TL;DR: In this paper, the exact Fock exchange operator for electronic structure calculations within the plane-wave pseudopotential method is described in detail for both molecular and periodic systems, and carefully validated.
Abstract: A new, very fast, implementation of the exact (Fock) exchange operator for electronic structure calculations within the plane-wave pseudopotential method is described in detail for both molecular and periodic systems, and carefully validated. Our method combines the recently proposed Adaptively Compressed Exchange approach, to reduce the number of times the exchange is evaluated in the self-consistent loop, with an orbital localization procedure that reduces the number of exchange integrals to be computed at each evaluation and potentially the compute time of each of them. The new implementation, already available in the Quantum ESPRESSO distribution, results in a speedup that is never smaller than 3-4x and that increases with the size of the system, according to various realistic benchmark calculations.
8 citations
University of Lorraine1, University of Paris2, University of Düsseldorf3, University of Warsaw4, University of Udine5, CentraleSupélec6, University of Western Australia7, University of Bern8, University of Copenhagen9, City University of New York10, Michigan State University11, Monash University12, Bruker13, Lund University14, Vienna University of Technology15, University of Jena16, University of Bremen17
1 citations