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As the first component of SPARC (Simulation Package for Ab-initio Real-space Calculations), we present an accurate and efficient finite-difference formulation and parallel implementation of Density Functional Theory (DFT) for isolated…

Computational Physics · Physics 2017-01-04 Swarnava Ghosh , Phanish Suryanarayana

We present a computationally efficient approach to perform systematically convergent real-space all-electron Kohn-Sham DFT calculations for solids using an enriched finite element (FE) basis. The enriched FE basis is constructed by…

Computational Physics · Physics 2021-08-18 Nelson D. Rufus , Bikash Kanungo , Vikram Gavini

The interpretation of future precise experiments on atomic parity violation in terms of parameters of the Standard Model could be hampered by uncertainties in the atomic and nuclear structure. While the former can be overcome by measurement…

Nuclear Theory · Physics 2008-11-26 B. Q. Chen , P. Vogel

Over many years, computational simulations based on Density Functional Theory (DFT) have been used extensively to study many different materials at the atomic scale. However, its application is restricted by system size, leaving a number of…

Mesoscale and Nanoscale Physics · Physics 2018-12-05 Carlos Romero-Muñiz , Ayako Nakata , Pablo Pou , David R. Bowler , Tsuyoshi Miyazaki , Rubén Pérez

The alignment of the frontier orbital energies of an adsorbed molecule with the substrate Fermi level at metal-organic interfaces is a fundamental observable of significant practical importance in nanoscience and beyond. Typical density…

Mesoscale and Nanoscale Physics · Physics 2017-03-07 Zhenfei Liu , David A. Egger , Sivan Refaely-Abramson , Leeor Kronik , Jeffrey B. Neaton

In this work we propose an efficient and accurate multi-scale optical simulation algorithm by applying a numerical version of slowly varying envelope approximation in FEM. Specifically, we employ the fast iterative method to quickly compute…

Optics · Physics 2024-12-03 Fan Xiao , Jingwei Wang , Zhongfei Xiong , Yuntian Chen

Calculation of statistical properties of nuclei in a finite-temperature mean-field theory requires projection onto good particle number, since the theory is formulated in the grand canonical ensemble. This projection is usually carried out…

Nuclear Theory · Physics 2018-01-23 P. Fanto , Y. Alhassid , G. F. Bertsch

For the Hirshfeld-I atom-in-molecule model, associated single-atom energies and interaction energies at the Hartree-Fock level are determined efficiently in one-electron Hilbert space. In contrast to most other approaches, the energy terms…

Background: Computationally tractable models of atomic nuclei is a long-time goal of nuclear structure physics. A flexible framework which easily includes excited states and many-body correlations is the configuration-interaction shell…

Nuclear Theory · Physics 2026-01-15 Y. X. Yu , Y. Lu , G. J. Fu , Calvin W. Johnson , Z. Z. Ren

The high cost associated with the evaluation of Hartree-Fock exchange (HFX) makes hybrid functionals computationally challenging for large systems. In this work, we present an efficient way to accelerate HFX calculations with numerical…

Computational Physics · Physics 2020-09-09 Xinming Qin , Jie Liu , Wei Hu , Jinlong Yang

In view of the difficulty in calculating the atomic structure parameters of high-$Z$ elements, the HFR (Hartree-Fock with relativistic corrections) theory in combination with the ridge regression (RR) algorithm rather than the Cowan code's…

Atomic Physics · Physics 2023-03-29 Yushu Yu , Chen Yang , Gang Jiang

In this article, we demonstrate the restricted Hartree-Fock electronic structure computation of the molecule $H_3^+$ through computational algebra. We approximate the Hartree-Fock total energy by a polynomial composed of LCAO coefficients…

Computational Physics · Physics 2024-05-15 Ichio Kikuchi , Akihito Kikuchi

We report Hartree-Fock (HF) based pseudopotentials suitable for plane-wave calculations. Unlike typical effective core potentials, the present pseudopotentials are finite at the origin and exhibit rapid convergence in a plane-wave basis;…

Materials Science · Physics 2008-02-28 W. A. Al-Saidi , E. J. Walter , A. M. Rappe

We estimate the prediction sensitivity with respect to Hartree-Fock exchange in approximate density functionals for representative Fe(II) and Fe(III) octahedral complexes. Based on the observation that the range of parameters spanned by the…

Materials Science · Physics 2015-07-16 Efthymios I. Ioannidis , Heather J. Kulik

The reported new algorithm determines the exact exchange potential v_x in a iterative way using energy and orbital shifts (ES, OS) obtained - with finite-difference formulas - from the solutions (occupied orbitals and their energies) of the…

Atomic Physics · Physics 2015-05-20 M. Cinal , A. Holas

The energy levels of the first few low-lying states of helium and lithium atoms in intense magnetic fields up to $\approx 10^8-10^9$~T are calculated in this study. A pseudospectral method is employed for the computational procedure. The…

Quantum Physics · Physics 2014-06-11 Anand Thirumalai , Jeremy S. Heyl

Many-electron systems at substantial finite temperatures and densities present a major challenge to density functional theory. Very little is known about the free-energy behavior over the temperature range of interest, for example, in the…

Materials Science · Physics 2012-01-25 Travis Sjostrom , Frank E. Harris , S. B. Trickey

Two different approximation schemes for the self-consistent solution of the relativistic Brueckner-Hartree-Fock equation for finite nuclei are discussed using realistic One-Boson-Exchange potentials. In a first scheme, the effects of…

Nuclear Theory · Physics 2009-10-22 R. Fritz , H. Müther

Modern density functional approximations achieve moderate accuracy at low computational cost for many electronic structure calculations. Some background is given relating the gradient expansion of density functional theory to the WKB…

Chemical Physics · Physics 2021-01-27 Kieron Burke

A new scheme for constructing approximate effective electron potentials within density-functional theory is proposed. The scheme consists of calculating the effective potential for a series of reference systems, and then using these…

Condensed Matter · Physics 2016-08-14 K. Stokbro , N. Chetty , K. W. Jacobsen , J. K. Nørskov