Optimised Projections for the Ab Initio Simulation of Large and Strongly Correlated Systems. 1st ed. 2012

種類:

電子ブック

責任表示:

by David D. O'Regan

出版情報:

Berlin, Heidelberg : Springer Berlin Heidelberg : Imprint: Springer, 2012

著者名:

• O'Regan, David D.
• SpringerLink (Online service)

シリーズ名:

Springer Theses, Recognizing Outstanding Ph.D. Research ;

ISBN:

9783642232381 [3642232388]    

注記:

An Introduction to Linear-Scaling Ab Initio Calculations -- Linear-Scaling DFT+U for Large Strongly-Correlated Systems.-  Projector Self-Consistent DFT+U Using Nonorthogonal Generalised Wannier Functions.-Linear-Scaling Ab Initio Calculations.-Linear-Scaling DFT+U for Large Strongly Correlated Systems.-  Optimised Projections for Strongly-Correlated Subspaces -- Projector Self-Consistent DFT +U Using Nonorthogonal  Generalised Wannier Functions -- Subspace Representations in Ab Initio Methods for Strongly Correlated Systems -- Tensorial  Consequences of Projection Optimisation -- Geometric Aspects of Representation Optimisation.-  A Numerical Study of Geometric Corrections for Representation Optimisation -- Tensorial Aspects of Calculating Hubbard U Interaction Parameters -- Discussion and Conclusion -- Appendix: Geometric Observations.
Density functional theory (DFT) has become the standard workhorse for quantum mechanical simulations as it offers a good compromise between accuracy and computational cost. However, there are many important systems for which DFT performs very poorly, most notably strongly-correlated materials, resulting in a significant recent growth in interest in 'beyond DFT'  methods. The widely used  DFT+U technique, in particular, involves the addition of explicit Coulomb repulsion terms to reproduce the physics of spatially-localised electronic subspaces. The magnitude of these corrective terms, measured by the famous Hubbard U parameter, has received much attention but less so for the projections used to delineate these subspaces. The dependence on the choice of these projections is studied in detail here and a method to overcome this ambiguity in DFT+U, by self-consistently determining the projections, is introduced. The author shows how nonorthogonal representations for electronic states may be used to construct thes

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