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The time-dependent complete-active-space self-consistent-field (TD-CASSCF) method for the description of multielectron dynamics in intense laser fields is presented, and a comprehensive description of the method is given. It introduces the…

Atomic Physics · Physics 2015-06-15 Takeshi Sato , Kenichi L. Ishikawa

The distributed adaptive signal fusion (DASF) framework allows to solve spatial filtering optimization problems in a distributed and adaptive fashion over a bandwidth-constrained wireless sensor network. The DASF algorithm requires each…

Signal Processing · Electrical Eng. & Systems 2025-05-02 Cem Ates Musluoglu , Alexander Bertrand

We employ a generalized variational principle to improve the stability, reliability, and precision of fully excited-state-specific complete active space self-consistent field theory. Compared to previous approaches that similarly seek to…

Chemical Physics · Physics 2022-09-05 Rebecca Hanscam , Eric Neuscamman

Unitary Coupled Cluster (UCC) theory is a promising variational method for electronic structure calculations, especially for strongly correlated systems and quantum computers. However, its practical application is limited by the steep…

Chemical Physics · Physics 2026-02-05 Prateek Vaish , Brenda Rubenstein

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

We describe the time-dependent restricted-active-space self-consistent-field (TD-RASSCF) method for a system of interacting bosons. We provide the theory of the method and discuss its numerical implementation. The method provides a general…

Quantum Physics · Physics 2017-04-28 Camille Lévêque , Lars Bojer Madsen

It is shown that a prechosen set of occupied/virtual valence/core atomic/fragmental orbitals can be transformed to an equivalent set of localized occupied/virtual pre-molecular orbitals (pre-LMO), which can then be taken as probes to select…

Chemical Physics · Physics 2021-05-12 Yibo Lei , Bingbing Suo , Wenjian Liu

Considering the emblematic Hartree-Fock (HF) energy expression with single Slater determinant and the ortho-normal molecular orbits (MO) in it, expressed as a linear combination (LC) of atomic orbits (LCAO) basis set functions, the HF…

Chemical Physics · Physics 2019-09-04 Sandor Kristyan

Perhaps the simplest first-principles approach to electronic structure is to fit the charge distribution of each orbital pair and use those fits wherever they appear in the entire electron-electron (EE) interaction energy. The charge…

Chemical Physics · Physics 2015-11-10 Brett I Dunlap , Mark C Palenik

Lattice networks with dissipative interactions can be used to describe the mechanics of discrete meso-structures of materials such as 3D-printed structures and foams. This contribution deals with the crack initiation and propagation in such…

Materials Science · Physics 2017-09-26 Ondřej Rokoš , Ron H. J. Peerlings , Jan Zeman , Lars A. A. Beex

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…

Neural network parametrizations have increasingly been used to represent the ground and excited states in variational Monte Carlo (VMC) with promising results. However, traditional VMC methods only optimize the wave function in regions of…

Computational Physics · Physics 2025-07-03 Huan Zhang , Robert J. Webber , Michael Lindsey , Timothy C. Berkelbach , Jonathan Weare

We present an efficient approach to simulate real-time quantum dynamics using Projected Variational Quantum Dynamics (PVQD), where the computational cost is reduced by strategically optimizing only a subset of the variational parameters at…

Quantum Physics · Physics 2026-01-06 Harshdeep Singh , Sonjoy Majumder , Sabyashachi Mishra

The variable-order fractional Laplacian plays an important role in the study of heterogeneous systems. In this paper, we propose the first numerical methods for the variable-order Laplacian $(-\Delta)^{\alpha({\bf x})/2}$ with $0 <…

Numerical Analysis · Mathematics 2024-02-06 Yixuan Wu , Yanzhi Zhang

Given a set of inelastic material models, a microstructure, a macroscopic structural geometry, and a set of boundary conditions, one can in principle always solve the governing equations to determine the system's mechanical response.…

Computational Engineering, Finance, and Science · Computer Science 2023-06-27 Ghina Jezdan , Sanjay Govindjee , Klaus Hackl

The variational free-Lagrange (VFL) method for shallow water is a free-Lagrange method with the additional property that it preserves the variational structure of shallow water. The VFL method was first derived in this context by…

Numerical Analysis · Mathematics 2010-01-28 Matthew Dixon , Todd Ringler

Variational wave functions used in the variational Monte Carlo (VMC) method are extensively improved to overcome the biases coming from the assumed variational form of the wave functions. We construct a highly generalized variational form…

Strongly Correlated Electrons · Physics 2008-10-27 Daisuke Tahara , Masatoshi Imada

We use the recently-developed Heat-bath Configuration Interaction (HCI) algorithm as an efficient active-space solver to perform multi-configuration self-consistent field calculations (HCISCF) with large active spaces. We give a detailed…

Chemical Physics · Physics 2018-11-08 James E. T. Smith , Adam A. Holmes , Bastien Mussard , Sandeep Sharma

The Hartree-Fock approximation for bosons employs variational wave functions that are a combination of permanents. These are bosonic counterpart of the fermionic Slater determinants, but with the significant distinction that the…

Quantum Gases · Physics 2025-03-03 B. R. Que , J. M. Zhang , H. F. Song , Y. Liu

We present a comparison of real-space methods based on regular grids for electronic structure calculations that are designed to have basis set variational properties, using as a reference the conventional method of finite differences (a…

Materials Science · Physics 2009-11-07 Chris-Kriton Skylaris , Oswaldo Dieguez , Peter D. Haynes , Mike C. Payne