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We present algebraic diagrammatic construction theory for simulating spin-orbit coupling and electron correlation in charged electronic states and photoelectron spectra. Our implementation supports Hartree-Fock and multiconfigurational…

Chemical Physics · Physics 2025-05-12 Rajat Majumder , Alexander Yu. Sokolov

We present the theory and implementation of a highly efficient relativistic third-order algebraic diagrammatic construction [ADC(3)] method based on a four-component (4c) Dirac-Coulomb (DC) Hamiltonian for the calculation of ionization…

Chemical Physics · Physics 2024-11-01 Sudipta Chakraborty , Tamoghna Mukhopadhyay , Malaya K. Nayak , Achintya Kumar Dutta

We consider finite element methods of multiscale type to approximate solutions for two-dimensional symmetric elliptic partial differential equations with heterogeneous $L^\infty$ coefficients. The methods are of Galerkin type and follow the…

Numerical Analysis · Mathematics 2025-05-20 Alexandre L. Madureira , Marcus Sarkis

In this work, two approaches for simulating X-ray absorption (XA) spectra with the complete active space self-consistent field (CASSCF) linear response (LR) method are introduced. The first approach employs the well-known core-valence…

Chemical Physics · Physics 2022-03-10 Benjamin Helmich-Paris

Determining the spin of any new particle and measuring its couplings to other particles and/or itself are crucial in reconstructing the structure of any quantum field theory containing the particle. A general helicity formalism is employed…

High Energy Physics - Phenomenology · Physics 2019-03-05 Seong Youl Choi , Jae Hoon Jeong , Ji Ho Song

In this paper, we consider the Dirac-Coulomb equation for many-particles, to describe the interaction between electrons in the system having many electrons. The four-component wave function will expanding into a finite basis-set, using…

Quantum Physics · Physics 2019-12-10 Bilal K. Jasim , Ayad A. Al-Ani , Saad N. Abood

I review the approach [1] to the one-loop low-energy effective action in the hypermultiplet sector for N=2 superconformal models. Any such a model contains an N=2 vector multiplet and some number of hypermultiplets. We found a general…

High Energy Physics - Theory · Physics 2008-05-22 N. G. Pletnev

An alternative methodology to evaluate two-electron-repulsion integrals based on numerical approximation is proposed. Computational chemistry has branched into two major fields with methodologies based on quantum mechanics and classical…

Chemical Physics · Physics 2016-09-22 Pedro E. M. Lopes

We present an implementation for the use of Cholesky decomposition (CD) of two-electron integrals within the spin-free Dirac-Coulomb (SFDC) scheme that enables to perform high-accuracy coupled-cluster (CC) calculations at costs almost…

Chemical Physics · Physics 2024-07-02 Tereza Uhlířová , Davide Cianchino , Tommaso Nottoli , Filippo Lipparini , Jürgen Gauss

Two dimensional massless Dirac Hamiltonian under the influence of hyperbolic magnetic fields is mentioned in curved space. Using a spherical surface parametrization, the Dirac operator on the sphere is presented and the system is given as…

Mathematical Physics · Physics 2014-07-01 Özlem Yeşiltaş

The continuous-time quantum Monte Carlo method is applied to the interacting resonant level model (IRLM) using double expansion with respect to Coulomb interaction Ufc and hybridization V. Thermodynamics of the IRLM without spin is…

Strongly Correlated Electrons · Physics 2015-07-30 Annamaria Kiss , Junya Otsuki , Yoshio Kuramoto

We propose a method for measuring spin Hamiltonians and apply it to the spin-1/2 Heisenberg antiferromagnet Cs2CuCl4, which shows a 2D fractionalized RVB state at low fields. By applying strong fields we fully align the spin moment of…

Strongly Correlated Electrons · Physics 2007-05-23 R. Coldea , D. A. Tennant , K. Habicht , P. Smeibidl , C. Wolters , Z. Tylczynski

This article offers a new approach for analysing the dynamic behaviour of distributions of charged particles in an electromagnetic field. After discussing the limitations inherent in the Lorentz-Dirac equation for a single point particle a…

Accelerator Physics · Physics 2007-05-23 David A. Burton , Jonathan Gratus , Robin W. Tucker

We present an implementation of relativistic ionization-potential (IP) equation-of-motion coupled-cluster (EOMCC) with up to 3-hole--2-particle (3h2p) excitations that makes use of the molecular mean-field exact two-component (mmfX2C)…

Chemical Physics · Physics 2025-01-10 Stephen H. Yuwono , Run R. Li , Tianyuan Zhang , Xiaosong Li , A. Eugene DePrince

We present detailed calculations of the magnetic ground state properties of Cs$_2$CuCl$_4$ in an applied magnetic field, and compare our results with recent experiments. The material is described by a spin Hamiltonian, determined with…

Strongly Correlated Electrons · Physics 2007-05-23 M. Y. Veillette , J. T. Chalker , R. Coldea

We present a systematic hierarchy of approximations for {\it local} exact-decoupling of four-component quantum chemical Hamiltonians based on the Dirac equation. Our ansatz reaches beyond the trivial local approximation that is based on a…

Chemical Physics · Physics 2012-06-28 Daoling Peng , Markus Reiher

We employ correlation-consistent effective core potentials (ccECPs) to perform exact or nearly exact correlation and total energy calculations for the fifth-row elements (Rb-Xe). Total energies are calculated using various correlated…

Materials Science · Physics 2025-12-22 Aqsa Shaikh , Omar Madany , Benjamin Kincaid , Lubos Mitas

In order for methods combining ab initio density-functional theory and many-body techniques to become routinely used, a flexible, fast, and easy-to-use implementation is crucial. We present an implementation of a general charge…

Noncollinear (NC) magnetism and spin-orbit coupling (SOC) are indispensable for predictive ab initio materials simulations with pronounced relativistic effects and magnetic frustration, yet they significantly increase the cost of…

We study an exactly solvable quantum field theory (QFT) model describing interacting fermions in 2+1 dimensions. This model is motivated by physical arguments suggesting that it provides an effective description of spinless fermions on a…

Mathematical Physics · Physics 2013-08-26 Jonas de Woul , Edwin Langmann