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In this work we consider a numerically solvable model of a two-electron diatomic molecule to study a recently proposed approximation based on the density-functional theory of so-called strictly correlated electrons (SCE). We map out the…

Strongly Correlated Electrons · Physics 2019-02-13 Luis Cort , Soeren Ersbak Bang Nielsen , Robert van Leeuwen

UGA-SSMRPT2, the spin-free perturbative analogue of Mukerjee's State-Specific Multireference Coupled Cluster Theory (MkMRCC) is known to be successful for size-extensive and intruder-free construction of dissociation curves. This work…

Chemical Physics · Physics 2026-02-05 Shamik Chanda , Pratyush Bhattacharjya , Avijit Sen , Sangita Sen

In this paper, we introduce a new scheme for the efficient numerical treatment of the electronic Schr\"odinger equation for molecules. It is based on the combination of a many-body expansion, which corresponds to the so-called bond order…

Numerical Analysis · Mathematics 2017-07-20 Sambasiva Rao Chinnamsetty , Michael Griebel , Jan Hamaekers

The article deals with the extension of the relativistic double-ionization equation-of-motion coupled-cluster (DI-EOMCC) method [H. Pathak et al. Phys. Rev. A 90, 010501(R) (2014)] for the molecular systems. The Dirac-Coulomb (DC)…

Chemical Physics · Physics 2020-04-22 Himadri Pathak , Sudip Sasmal , Kaushik Talukdar , Malaya K. Nayak , Nayana Vaval , Sourav Pal

The adiabatic connection formalism, usually based on the first-order perturbation theory, has been generalized to an arbitrary order. The generalization stems from the observation that the formalism can be derived from a properly arranged…

Chemical Physics · Physics 2023-10-18 Andreas Savin , Jacek Karwowski

Multi-configurational electronic structure theory delivers the most versatile approximations to many-electron wavefunctions, flexible enough to deal with all sorts of transformations, ranging from electronic excitations, to open-shell…

Chemical Physics · Physics 2024-05-07 Kalman Szenes , Maximilian Moerchen , Paul Fischill , Markus Reiher

The equation of motion coupled cluster singles and doubles model (EOM-CCSD) is an accurate, black-box correlated electronic structure approach to investigate electronically excited states and electron attachment or detachment processes. It…

Chemical Physics · Physics 2023-09-18 Loïc Halbert , Andre Severo Pereira Gomes

This paper is devoted to the numerical symplectic approximation of the charged-particle dynamics (CPD) with arbitrary electromagnetic fields. By utilizing continuous-stage methods and exponential integrators, a general class of symplectic…

Numerical Analysis · Mathematics 2022-07-05 Ting Li , Bin Wang

The open-shell reference relativistic equation-of-motion coupled-cluster method within its four-component description is successfully implemented with the consideration of single- and double- excitation approximation. The one-body and…

Atomic Physics · Physics 2016-09-21 Himadri Pathak , Sudip Sasmal , Malaya K. Nayak , Nayana Vaval , Sourav Pal

We design a quantum molecular dynamics method for strongly correlated electron metals. The strong electronic correlation effects are treated within a real-space version of the Gutzwiller variational approximation (GA), which is suitable for…

Strongly Correlated Electrons · Physics 2017-07-12 Jean-Pierre Julien , Joel D. Kress , Jian-Xin Zhu

We construct, analyse and assess various schemes of second order of accuracy in space and time for model advection-diffusion-reaction differential equations. The constructed schemes are meant to be of practical use in solving industrial…

Numerical Analysis · Mathematics 2023-01-25 Saray Busto , Eleuterio F. Toro , Maria Elena Vazquez-Cendon

The primary computational challenge when simulating nonadiabatic ab initio molecular dynamics is the unfavorable compute costs of electronic structure calculations with molecular size. Simple electronic structure theories, like…

Chemical Physics · Physics 2023-06-28 Justin J. Talbot , Martin Head-Gordon , Stephen J. Cotton

We present a stochastic approach to perform strongly contracted n-electron valence state perturbation theory (SC-NEVPT), which only requires one- and two-body reduced density matrices, without introducing approximations. We use this method…

Chemical Physics · Physics 2021-01-05 Nick S. Blunt , Ankit Mahajan , Sandeep Sharma

In this study, two different simple and intuitive semiempirical schemes for computing approximate non-adiabatic coupling vectors (NACVs) between the ground and excited electronic states are presented. The first approximation makes use of…

Chemical Physics · Physics 2019-08-02 Alexander Humeniuk , Roland Mitrić

This paper presents a multi-resolution reconstruction method for Electrical Impedance Tomography (EIT), referred to as MR-EIT, which is capable of operating in both supervised and unsupervised learning modes. MR-EIT integrates an ordered…

Computer Vision and Pattern Recognition · Computer Science 2025-03-04 Fangming Shi , Jinzhen Liu , Xiangqian Meng , Yapeng Zhou , Hui Xiong

A linear-algebraic theory called 'multiple Arnoldi method' is presented and realizes large-scale (order-N) electronic structure calculation with generalized eigen-value equations. A set of linear equations, in the form of (zS-H) x = b, are…

Materials Science · Physics 2012-04-04 T. Hoshi , S. Yamamoto , T. Fujiwara , T. Sogabe , S. -L. Zhang

Analytic first and second derivatives of the energy are developed for the fragment molecular orbital method interfaced with molecular mechanics in the electrostatic embedding scheme at the level of Hartree-Fock and density functional…

Chemical Physics · Physics 2020-05-19 Hiroya Nakata , Dmitri G. Fedorov

We present the first calculation for many-electron atoms complete through fourth order of many-body perturbation theory. Owing to an overwhelmingly large number of underlying diagrams, we developed a suite of symbolic algebra tools to…

Atomic Physics · Physics 2007-05-23 Caleb C. Cannon , Andrei Derevianko

A model-operator approach to fully relativistic calculations of the nuclear recoil effect on energy levels in many-electron atomic systems is worked out. The one-electron part of the model operator for treating the normal mass shift beyond…

In the previous paper of this series [JCTC 2020, 16, 3757], we presented a theoretical and algorithmic framework based on a localized representation of the occupied space that exploits the inherent sparsity in the real-space evaluation of…

Materials Science · Physics 2021-11-16 Hsin-Yu Ko , Biswajit Santra , Robert A. DiStasio
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