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We present a practical semiclassical method for computing the electron spin dynamics of a radical in which the electron spin is hyperfine coupled to a large number of nuclear spins. This can be used to calculate the singlet and triplet…

Chemical Physics · Physics 2014-07-09 David E. Manolopoulos , P. J. Hore

We analyze the low-energy spectrum of a two-electron double quantum dot under a potential bias in the presence of an external magnetic field. We focus on the regime of spin blockade, taking into account the spin orbit interaction and…

Mesoscale and Nanoscale Physics · Physics 2013-05-30 Dimitrije Stepanenko , Mark Rudner , Bertrand I. Halperin , Daniel Loss

We present a non-canonically symplectic integration scheme tailored to numerically computing the post-Newtonian motion of a spinning black-hole binary. Using a splitting approach we combine the flows of orbital and spin contributions. In…

General Relativity and Quantum Cosmology · Physics 2010-05-25 Christian Lubich , Benny Walther , Bernd Bruegmann

A general formula for the orbital magnetic moment of interacting electrons in solids is derived using the many-electron Green function method. The formula factorizes into two parts, a part that contains the information about the…

Materials Science · Physics 2016-04-20 F. Aryasetiawan , K. Karlsson , T. Miyake

Atomic comagnetometers are used in searches for anomalous spin-dependent interactions. Magnetic field gradients are one of the major sources of systematic errors in such experiments. Here we describe a comagnetometer based on the nuclear…

Atomic Physics · Physics 2018-07-18 Teng Wu , John W. Blanchard , Derek F. Jackson Kimball , Min Jiang , Dmitry Budker

An energy functional for orbital based $O(N)$ calculations is proposed, which depends on a number of non orthogonal, localized orbitals larger than the number of occupied states in the system, and on a parameter, the electronic chemical…

mtrl-th · Physics 2016-09-07 Jeongnim Kim , Francesco Mauri , Giulia Galli

We present a practical algorithm to compute models of rational functions with minimal resultant under conjugation by fractional linear transformations. We also report on a search for rational functions of degrees 2 and 3 with rational…

Number Theory · Mathematics 2019-02-20 Nils Bruin , Alexander Molnar

We present the theory of analytical Hartree-Fock gradients for periodic systems as implemented in the code CRYSTAL. We demonstrate how derivatives of the integrals can be computed with the McMurchie-Davidson algorithm. Highly accurate…

Materials Science · Physics 2007-05-23 K. Doll , V. R. Saunders , N. M. Harrison

An ensemble Green's function formalism, based on the von Neumann density matrix approach, to calculate one-electron excitation spectra of a many-electron system with degenerate ground states is proposed. A set of iterative equations for the…

Strongly Correlated Electrons · Physics 2019-12-24 Erik Linnér , Ferdi Aryasetiawan

The multiscale model combining the multiconfigurational self-consistent field (MCSCF) method with the fully atomistic polarizable Fluctuating Charges (FQ) force field (J. Chem. Theory Comput. 2024, 20, 9954-9967) is here extended to the…

Chemical Physics · Physics 2025-11-14 Francesco Mazza , Marco Trinari , Chiara Sepali , Chiara Cappelli

For a given many-electron molecule, it is possible to define a corresponding one-electron Schr\"odinger equation, using potentials derived from simple atomic densities, whose solution predicts fairly accurate molecular orbitals for single-…

Chemical Physics · Physics 2022-05-16 Fariba Nazari , Jerry L. Whitten

A fully analytical approximation for the observable characteristics of many-electron atoms is developed via a complete and orthonormal hydrogen-like basis with a single-effective charge parameter for all electrons of a given atom. The basis…

Quantum Physics · Physics 2017-12-06 O. D. Skoromnik , I. D. Feranchuk , A. U. Leonau , C. H. Keitel

We propose an exact algorithm for computing the analytical gradient within the framework of the orbital-specific-virtual (OSV) second-order M{\o}ller-Plesset (MP2) theory in resolution-of-identity (RI) approximation. We implement the exact…

Chemical Physics · Physics 2019-12-17 Ruiyi Zhou , Qiujiang Liang , Jun Yang

We present a novel route to constructing cost-efficient semi-empirical approximations for the non-additive kinetic energy in subsystem density functional theory. The developed methodology is based on the use of Slater determinants composed…

Chemical Physics · Physics 2025-01-13 Larissa Sophie Eitelhuber , Denis G. Artiukhin

The current work presents a natural orbital functional (NOF) for electronic systems with any spin value independent of the external potential being considered, that is, a global NOF (GNOF). It is based on a new two-index reconstruction of…

Chemical Physics · Physics 2021-12-07 Mario Piris

The exchange-correlation energy in Kohn-Sham density functional theory is expressed as a functional of the electronic density and the Kohn-Sham orbitals. An alternative to Kohn-Sham theory is to express the energy as a functional of the…

Computational Physics · Physics 2009-10-31 S. Goedecker , C. Umrigar

We present a method for measuring magnetic field gradients with macroscopic singlet states realized with ensembles of spin-j particles. While the singlet state is completely insensitive to homogeneous magnetic fields, the variance of its…

Quantum Physics · Physics 2015-01-27 Inigo Urizar-Lanz , Philipp Hyllus , Inigo L. Egusquiza , Morgan W. Mitchell , Geza Toth

In this paper, we propose an orbital iteration based parallel approach for electronic structure calculations. This approach is based on our understanding of the single-particle equations of independent particles that move in an effective…

Numerical Analysis · Mathematics 2014-11-06 Xiaoying Dai , Xingao Gong , Aihui Zhou , Jinwei Zhu

We report the development of the theory and computer program for analytical nuclear energy gradients for (extended) multi-state complete active space perturbation theory (CASPT2) with full internal contraction. The vertical shifts are also…

Chemical Physics · Physics 2017-03-20 Bess Vlaisavljevich , Toru Shiozaki

A common problem in physics and engineering is the calculation of the minima of energy functionals. The theory of Sobolev gradients provides an efficient method for seeking the critical points of such a functional. We apply the method to…

Computational Physics · Physics 2009-11-10 S. Sial , J. Neuberger , T. Lookman , A. Saxena