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Computationally-efficient semilocal approximations of density functional theory at the level of the local spin density approximation (LSDA) or generalized gradient approximation (GGA) poorly describe weak interactions. We show improved…

In ab initio pseudopotential calculations within density-functional theory the nonlinear exchange-correlation interaction between valence and core electrons is often treated linearly through the pseudopotential. We discuss the accuracy and…

Materials Science · Physics 2009-10-30 Martin Fuchs , Michel Bockstedte , Eckhard Pehlke , Matthias Scheffler

Semilocal density functionals for the exchange-correlation energy are needed for large electronic systems. The Tao-Perdew-Staroverov-Scuseria (TPSS) meta-generalized gradient approximation (meta-GGA) is semilocal and usefully accurate, but…

Materials Science · Physics 2009-06-30 John P. Perdew , Adrienn Ruzsinszky , Gabor I. Csonka , Lucian A. Constantin , Jianwei Sun

First-principles calculations within the weighted density approximation (WDA) were performed for ground state properties of ferroelectric perovskites PbTiO$_3$, BaTiO$_3$, SrTiO$_3$, KNbO$_3$ and KTaO$_3$. We used the plane-wave…

Materials Science · Physics 2009-11-10 Zhigang Wu , R. E. Cohen , D. J. Singh

In recent years, the use of Monte Carlo (MC) simulations in the domain of Medical Physics has become a state-of-the-art technology that consumes lots of computational resources for the accurate prediction of particle interactions. The use…

We use an all-electron implementation of the GW approximation to analyze several possible sources of error in the theory and its implementation. Among these are convergence in the polarization and Green's functions, the dependence of QP…

Materials Science · Physics 2013-05-29 M. van Schilfgaarde , T. Kotani , S. Faleev

A successful measurement of the Stochastic Gravitational Wave Background (SGWB) in Pulsar Timing Arrays (PTAs) would open up a new window through which to test the predictions of General Relativity (GR). We consider how these measurements…

Cosmology and Nongalactic Astrophysics · Physics 2025-05-29 Qiuyue Liang , Meng-Xiang Lin , Mark Trodden

Coarse-graining (CG) of molecular simulations simplifies the particle representation by grouping selected atoms into pseudo-beads and drastically accelerates simulation. However, such CG procedure induces information losses, which makes…

Machine Learning · Computer Science 2022-06-20 Wujie Wang , Minkai Xu , Chen Cai , Benjamin Kurt Miller , Tess Smidt , Yusu Wang , Jian Tang , Rafael Gómez-Bombarelli

Theoretical positron lifetime values have been calculated systematically 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…

Materials Science · Physics 2024-02-12 J. M. Campillo Robles , E. Ogando , F. Plazaola

This paper presents an Accelerated Preconditioned Proximal Gradient Algorithm (APPGA) for effectively solving a class of Positron Emission Tomography (PET) image reconstruction models with differentiable regularizers. We establish the…

Optimization and Control · Mathematics 2024-09-23 Yizun Lin , Yongxin He , C. Ross Schmidtlein , Deren Han

A conforming discontinuous Galerkin (DG) finite element method has been introduced in [21] on simplicial meshes, which has the flexibility of using discontinuous approximation and the simplicity in formulation of the classic continuous…

Numerical Analysis · Mathematics 2019-07-11 Xiu Ye , Shangyou Zhang

We present the two-dimensional unstructured grids extension of the a posteriori local subcell correction of discontinuous Galerkin (DG) schemes introduced in [52]. The technique is based on the reformulation of DG scheme as a finite volume…

Numerical Analysis · Mathematics 2022-12-23 François Vilar , Rémi Abgrall

By using the quantum Ising chain as a test bed and treating the spin polarization along the external transverse field as the "generalized density", we examine the performance of different levels of density functional approximations parallel…

Computational Physics · Physics 2021-10-27 Jiahao Mao , Haifeng Tang , Wenhui Duan , Zheng Liu

Unlike the local density approximation (LDA) and the generalized gradient approximation (GGA), calculations with meta-generalized gradient approximations (meta-GGA) are usually done according to the generalized Kohn-Sham (gKS) formalism.…

Materials Science · Physics 2016-06-01 Zeng-hui Yang , Haowei Peng , Jianwei Sun , John P. Perdew

Expansion of Standard Model for the quantitative description of the orthopositronium lifetime anomalies (from QED to supersymmetric QED) allows to formulate experimental tests of supervision of additional realization of the supersymmetry in…

Quantum Physics · Physics 2007-05-23 B. M. Levin , V. I. Sokolov

We introduce a generalization (gLDA) of the traditional Local Density Approximation (LDA) within density functional theory. The gLDA uses both the one-electron Seitz radius $\rs$ and a two-electron hole curvature parameter $\eta$ at each…

Chemical Physics · Physics 2015-06-18 Pierre-François Loos , Caleb J. Ball , Peter M. W. Gill

We study two techniques for correcting the geometrical error associated with domain approximation by a polygon. The first was introduced some time ago \cite{bramble1972projection} and leads to a nonsymmetric formulation for Poisson's…

Numerical Analysis · Mathematics 2020-01-10 Todd Dupont , Johnny Guzman , Ridgway Scott

We describe a post-Minkowskii approximation of general relativity as a power series expansion in G, Newton's gravitational constant. Material sources are hidden behind boundaries, and only the vacuum Einstein equations are considered. An…

General Relativity and Quantum Cosmology · Physics 2010-05-12 Steven Detweiler , Lee H. Brown

For orbital-free {\it ab initio} molecular dynamics, especially on systems in extreme thermodynamic conditions, we provide the first pseudo-potential-adapted generalized gradient approximation (GGA) functional for the non-interacting free…

Chemical Physics · Physics 2020-02-19 Kai Luo , Valentin V. Karasiev , S. B. Trickey

Gradient pattern analysis (GPA) is a well-established technique for measuring gradient bilateral asymmetries of a square numerical lattice. This paper introduces an improved version of GPA designed for galaxy morphometry. We show the…