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Based on the first-principles calculations, we perform an initiatory statistical assessment on the reliability level of theoretical positron lifetime of bulk material. We found the original generalized gradient approximation (GGA) form of…

Computational Physics · Physics 2015-10-23 Wenshuai Zhang , Bingchuan Gu , Jiandang Liu , Bangjiao Ye

Several first-principles calculations of positron-annihilation characteristics in solids have added gradient corrections to the local-density approximation within the theory by Arponen and Pajanne [Ann. Phys. (N.Y.) 121, 343 (1979)] since…

Materials Science · Physics 2014-07-16 Jan Kuriplach , Bernardo Barbiellini

We present first-principles approaches based on density functional theory for calculating positron states and annihilation characteristics in condensed matter. The treatment of the electron-positron correlation effects (the enhancement of…

Materials Science · Physics 2007-05-23 B. Barbiellini , M. Hakala , R. M. Nieminen , M. J. Puska

Positron annihilation spectroscopy is often used to analyze the local electronic structure of materials of technological interest. Reliable theoretical tools are crucial to interpret the measured spectra. Here, we propose a parameter-free…

Materials Science · Physics 2015-04-15 Bernardo Barbiellini , Jan Kuriplach

We present a study of the equilibrium properties of $sp$-bonded solids within the pseudopotential approach, employing recently proposed generalized gradient approximation (GGA) exchange correlation functionals. We analyze the effects of the…

Condensed Matter · Physics 2016-08-31 Yumin Juan , Efthimios Kaxiras

Successful modern generalized gradient approximations (GGA) are biased toward atomic energies. Restoration of the first-principles gradient expansion for the exchange energy over a wide range of density gradients eliminates this bias. We…

We present a new nonempirical density functional generalized gradient approximation (GGA) that gives significant improvements for lattice constants, crystal structures, and metal surface energies over the most popular Perdew-Burke-Ernzerhof…

Materials Science · Physics 2009-11-11 Zhigang Wu , Ronald E. Cohen

We make a gradient correction to a new local density approximation form of positron-electron correlation. Then the positron lifetimes and affinities are probed by using these two approximation forms based on three electronic-structure…

Materials Science · Physics 2015-09-25 Wen-Shuai Zhang , Bing-Chuan Gu , Xiao-Xi Han , Jian-Dang Liu , Bang-Jiao Ye

Significant advances in deep learning have led to more widely used and precise neural network-based generative models such as Generative Adversarial Networks (GANs). We introduce a post-hoc correction to deep generative models to further…

High Energy Physics - Phenomenology · Physics 2020-12-30 Sascha Diefenbacher , Engin Eren , Gregor Kasieczka , Anatolii Korol , Benjamin Nachman , David Shih

We present an analysis of positron lifetimes in solids with unprecedented depth. Instead of modeling correlation effects with density functionals, we study positron-electron wave functions with long-range correlations included. This gives…

Other Condensed Matter · Physics 2022-10-18 K. A. Simula , J. E. Muff , I. Makkonen , N. D. Drummond

Positron lifetimes have been calculated in bulk and monovacancies for most of the elements of the periodic table. Self-consistent and non-self-consistent schemes have been used for the calculation of the electronic structure in the solid,…

Materials Science · Physics 2024-02-08 J. M. Campillo-Robles , E. Ogando , F. Plazaola

Successful modern generalized gradient approximations (GGA's) are biased toward atomic energies. Restoration of the first-principles gradient expansion for exchange over a wide range of density gradients eliminates this bias. We introduce…

The ground-state energy, electron density, and related properties of ordinary matter can be computed efficiently when the exchange-correlation energy as a functional of the density is approximated semilocally. We propose the first meta-GGA…

Materials Science · Physics 2015-06-25 Jianwei Sun , Adrienn Ruzsinszky , John P. Perdew

A simple, novel, non-empirical, constraint-based orbital-free generalized gradient approximation (GGA) non-interacting kinetic energy density functional is presented along with illustrative applications. The innovation is adaptation of…

Chemical Physics · Physics 2018-08-01 K. Luo , V. V. Karasiev , S. B. Trickey

The Jacob's ladder of density functional theory (DFT) proposes the compelling view that by extending the form of successful approximations -- being guided by exact conditions and selected (least empirical) norms -- upper rungs will do…

Materials Science · Physics 2025-02-25 Jacques K. Desmarais , Alessandro Erba , Giovanni Vignale , Stefano Pittalis

Variance-reduced stochastic gradient methods have gained popularity in recent times. Several variants exist with different strategies for the storing and sampling of gradients and this work concerns the interactions between these two…

Optimization and Control · Mathematics 2022-10-19 Martin Morin , Pontus Giselsson

Functionals of the meta-generalized gradient approximation (MGGA) are nowadays widely used in chemistry and solid-state physics for the simulation of electronic systems like molecules, solids, or surfaces. Due to their dependency on the…

Materials Science · Physics 2022-05-31 Jan Doumont , Fabien Tran , Peter Blaha

Meta-generalized gradient approximations (meta-GGAs) on the third rung of the functional hierarchy are gaining increasing relevance for the electronic structure. Meta-GGAs are constructed from numerous ingredients including the orbital…

Materials Science · Physics 2025-06-05 Ashesh Giri , Chandra Shahi , Adrienn Ruzsinszky

One of the standard generalized-gradient approximations (GGAs) in use in modern electronic-structure theory, PBE, and a recently proposed modification designed specifically for solids, PBEsol, are identified as particular members of a…

Materials Science · Physics 2015-05-13 Luana S. Pedroza , Antonio J. R. da Silva , Klaus Capelle

The electron density, its gradient, and the Kohn-Sham orbital kinetic energy density are the local ingredients of a meta-generalized gradient approximation (meta-GGA). We construct a meta-GGA density functional for the exchange-correlation…

Materials Science · Physics 2009-02-20 Jianmin Tao , John P. Perdew , Viktor N. Staroverov , Gustavo E. Scuseria
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