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Explicitly-correlated F12 methods are becoming the first choice for high-accuracy molecular orbital calculations, and can often achieve chemical accuracy with relatively small gaussian basis sets. In most calculations, the many three- and…

Chemical Physics · Physics 2016-05-25 Giuseppe M. J. Barca , Pierre-François Loos , Peter M. W. Gill

In this article, we analyse an integral equation of the second kind that represents the solution of $N$ interacting dielectric spherical particles undergoing mutual polarisation. A traditional analysis can not quantify the scaling of the…

Numerical Analysis · Mathematics 2020-07-14 Muhammad Hassan , Benjamin Stamm

Most modern calculations of many-electron atoms use basis sets of atomic orbitals. An accurate account for the electronic correlations in heavy atoms is very difficult computational problem and optimization of the basis sets can reduce…

Atomic Physics · Physics 2024-01-17 M. G. Kozlov , Yu. A. Demidov , M. Y. Kaygorodov , E. V. Triapitsyna

Random fields on the sphere play a fundamental role in the natural sciences. This paper presents a simulation algorithm parenthetical to the spectral turning bands method used in Euclidean spaces, for simulating scalar- or vector-valued…

Statistics Theory · Mathematics 2020-03-31 Alfredo Alegría , Xavier Emery , Christian Lantuéjoul

Spherical harmonics provide a smooth, orthogonal, and symmetry-adapted basis to expand functions on a sphere, and they are used routinely in physical and theoretical chemistry as well as in different fields of science and technology, from…

Chemical Physics · Physics 2023-05-02 Filippo Bigi , Guillaume Fraux , Nicholas J. Browning , Michele Ceriotti

Subspaces obtained by the orthogonal projection of locally supported square-integrable vector fields onto the Hardy spaces $H_+(\mathbb{S})$ and $H_-(\mathbb{S})$, respectively, play a role in various inverse potential field problems since…

Numerical Analysis · Mathematics 2023-07-06 Christian Gerhards , Xinpeng Huang

In the article [11] of L. Kunyansky a symmetric integral identity for Bessel functions of the first and second kind was proved in order to obtain an explicit inversion formula for the spherical mean transform where our data is given on the…

Analysis of PDEs · Mathematics 2019-05-22 Yehonatan Salman

A simple real-space model for the free-electron wavefunction with spin is proposed, based on coherent vortices on the scale of h/mc, rotating at mc^2/h. This reproduces the proper values for electron spin and magnetic moment. Transformation…

Quantum Physics · Physics 2007-05-23 Alan M. Kadin

Spectral approximation and variational inducing learning for the Gaussian process are two popular methods to reduce computational complexity. However, in previous research, those methods always tend to adopt the orthonormal basis functions,…

Machine Learning · Statistics 2021-07-15 Wenqi Fang , Guanlin Wu , Jingjing Li , Zheng Wang , Jiang Cao , Yang Ping

A simple approximation within the framework of the hybrid methods for the calculation of the electronic structure of solids is presented. By considering only the diagonal elements of the perturbation operator (Hartree-Fock exchange minus…

Materials Science · Physics 2012-01-31 Fabien Tran

An explicit form of the functional measure on the factor space $Diff^{1}_{+}(S^{1})/SL(2,\textbf{R})$ is obtained that makes Schwarzian functional integrals calculus simpler and more transparent.

High Energy Physics - Theory · Physics 2019-12-18 Vladimir V. Belokurov , Evgeniy T. Shavgulidze

We implement an efficient method of computation of two dimensional Fourier-type integrals based on approximation of the integrand by Gaussian radial basis functions, which constitute a standard tool in approximation theory. As a result, we…

Numerical Analysis · Mathematics 2022-02-07 A. Martinez-Finkelshtein , D. Ramos-Lopez , D. R. Iskander

The SO(5)>SO(3) spherical harmonics form a natural basis for expansion of nuclear collective model angular wave functions. They underlie the recently-proposed algebraic method for diagonalization of the nuclear collective model Hamiltonian…

Computational Physics · Physics 2009-06-19 M. A. Caprio , D. J. Rowe , T. A. Welsh

A mixed basis approach based on density functional theory is extended to one-dimensional(1D) systems. The basis functions here are taken to be the localized B-splines for the two finite non-periodic dimensions and the plane waves for the…

Materials Science · Physics 2016-04-20 Chung-Yuan Ren , Yia-Chung Chang , Chen-Shiung Hsue

We propose here a single Pfaffian correlated variational ansatz, that dramatically improves the accuracy with respect to the single determinant one, while remaining at a similar computational cost. A much larger correlation energy is indeed…

Chemical Physics · Physics 2020-07-28 Claudio Genovese , Tomonori Shirakawa , Kousuke Nakano , Sandro Sorella

Free-particle Green's function plays a central role in the theoretical description of electron scattering and autoionization processes in quantum physics and chemistry. Recently, Gaussian basis set approaches have become increasingly…

Chemical Physics · Physics 2026-05-19 Dibyendu Mahato , Wojciech Skomorowski

A general method is described for finding algebraic expressions for matrix elements of any one- and two-particle operator for an arbitrary number of subshells in an atomic configuration, requiring neither coefficients of fractional…

Atomic Physics · Physics 2009-11-10 G. Gaigalas , Z. Rudzikas , C. Froese Fischer

The semilinear stochastic wave equation on the sphere driven by multiplicative Gaussian noise is discretized by a stochastic trigonometric integrator in time and a spectral Galerkin approximation in space based on the spherical harmonic…

Numerical Analysis · Mathematics 2026-02-03 David Cohen , Stefano Di Giovacchino , Annika Lang

Two electrons at the threshold of ionization represent a severe test case for electronic structure theory. A pseudospectral method yields a very accurate density of the two-electron ion with nuclear charge close to the critical value.…

Chemical Physics · Physics 2014-08-12 Paul E. Grabowski , Kieron Burke

We introduce and develop the notion of spherical polyharmonics, which are a natural generalisation of spherical harmonics. In particular we study the theory of zonal polyharmonics, which allows us, analogously to zonal harmonics, to…

Analysis of PDEs · Mathematics 2019-12-03 Hubert Grzebuła , Sławomir Michalik
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