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We report the derivation and implementation of orbital optimization algorithms for the active space decomposition (ASD) model, which are extensions of complete active space self-consistent field (CASSCF) and its occupation-restricted…

Chemical Physics · Physics 2015-08-17 Inkoo Kim , Shane M. Parker , Toru Shiozaki

We introduce an efficient finite-element approach for large-scale real-space pseudopotential density functional theory (DFT) calculations incorporating noncollinear magnetism and spin-orbit coupling. The approach, implemented within the…

Materials Science · Physics 2025-06-11 Nikhil Kodali , Phani Motamarri

A new, very fast, implementation of the exact (Fock) exchange operator for electronic structure calculations within the plane-wave pseudopotential method is described in detail for both molecular and periodic systems, and carefully…

Materials Science · Physics 2018-12-12 Ivan Carnimeo , Stefano Baroni , Paolo Giannozzi

Analytic energy gradients are presented for a variational two-electron reduced-density-matrix-driven complete active space self-consistent field (v2RDM-CASSCF) procedure that employs the density-fitting (DF) approximation to the…

Chemical Physics · Physics 2018-11-29 J. Wayne Mullinax , Evgeny Epifanovsky , Gergely Gidofalvi , A. Eugene DePrince

For the parallel computation of partial differential equations, one key is the grid partitioning. It requires that each process owns the same amount of computations, and also, the partitioning quality should be proper to reduce the…

Distributed, Parallel, and Cluster Computing · Computer Science 2017-02-02 Hui Liu , Tao Cui , Wei Leng , Linbo Zhang

We consider adaptive finite element methods for solving a multiscale system consisting of a macroscale model comprising a system of reaction-diffusion partial differential equations coupled to a microscale model comprising a system of…

Numerical Analysis · Mathematics 2015-06-22 A. Johansson , J. H. Chaudry , V. Carey , D. Estep , V. Ginting , M. Larson , S. Tavener

Simulation of 3D low-frequency electromagnetic fields propagating in the Earth is computationally expensive. We present a fictitious wave domain high-order finite-difference time-domain (FDTD) modelling method on nonuniform grids to compute…

Numerical Analysis · Mathematics 2023-02-13 Pengliang Yang , Rune Mittet

We propose to adapt the confined pseudo-atomic orbitals underpinning the precalculated Slater-Koster (SK) interaction tables in Density Functional Tight Binding (DFTB) to local atomic environments. We demonstrate significant improvement in…

In this paper, we propose an adaptive fast solver for a general class of symmetric positive definite (SPD) matrices which include the well-known graph Laplacian. We achieve this by developing an adaptive operator compression scheme and a…

Numerical Analysis · Mathematics 2018-03-06 Thomas Y. Hou , D. Huang , K. C. Lam , P. Zhang

High-precision direction-of-arrival (DOA) estimation, as a key sensing capability for 6G-enabled applications such as autonomous driving and extended reality, is increasingly dependent on the effective exploitation of spatial degrees of…

Signal Processing · Electrical Eng. & Systems 2026-04-16 Ye Tian , Jiaji Ren , Tuo Wu , Wei Liu , Maged Elkashlan , Matthew C. Valenti , Naofal Al-Dhahir , Hing Cheung So

A more accurate, stable, finite-difference time-domain (FDTD) algorithm is developed for simulating Maxwell's equations with isotropic or anisotropic dielectric materials. This algorithm is in many cases more accurate than previous…

Computational Physics · Physics 2015-06-12 Gregory R. Werner , Carl A. Bauer , John R. Cary

Computational Fluid Dynamics (CFD) simulations are essential for analyzing and optimizing fluid flows in a wide range of real-world applications. These simulations involve approximating the solutions of the Navier-Stokes differential…

Differentiable programming has facilitated numerous methodological advances in scientific computing. Physics engines supporting automatic differentiation have simpler code, accelerating the development process and reducing the maintenance…

Computational Physics · Physics 2023-04-04 Chuin Wei Tan , Chris J. Pickard , William C. Witt

A multi-fidelity (MF) active learning method is presented for design optimization problems characterized by noisy evaluations of the performance metrics. Namely, a generalized MF surrogate model is used for design-space exploration,…

Optimization and Control · Mathematics 2022-07-12 Riccardo Pellegrini , Jeroen Wackers , Riccardo Broglia , Andrea Serani , Michel Visonneau , Matteo Diez

The Finite Difference Time Domain (FDTD) method is a widely used numerical technique for solving Maxwell's equations, particularly in computational electromagnetics and photonics. It enables accurate modeling of wave propagation in complex…

Computation and Language · Computer Science 2025-04-15 Yifei He , Måns I. Andersson , Stefano Markidis

The finite element analysis of high frequency vibrations of quartz crystal plates is a necessary process required in the design of quartz crystal resonators of precision types for applications in filters and sensors. The anisotropic…

Computational Physics · Physics 2015-09-21 Ji Wang , Lihong Wang , Qiang Sun , Rongxing Wu , Bin Huang , Jianke Du , Wei Xiang

This paper introduces an effcient class of adaptive stencil extension reconstruction methods based on a discontinuity feedback factor, addressing the challenges of weak robustness and high computational cost in high-order schemes,…

Numerical Analysis · Mathematics 2024-10-10 Hong Zhang , Yue Zhao , Xing Ji , Kun Xu

This paper is concerned with the optimal error estimates and energy conservation properties of the alternating direction implicit finite-difference time-domain (ADI-FDTD) method which is a popular scheme for solving the 3D Maxwell…

Numerical Analysis · Mathematics 2011-06-02 Liping Gao , Bo Zhang

The inverse design of nonlocal metasurfaces requires the precise optimization of lattice geometry to engineer spatial dispersion and high-Q resonances. However, gradient-based optimization is frequently bottle-necked by the evaluation of…

Optics · Physics 2026-03-05 Mingcan Qin , Yifeng Qin

We show that the central finite difference formula for the first and the second derivative of a function can be derived, in the context of quantum mechanics, as matrix elements of the momentum and kinetic energy operators using, as a basis…

Quantum Physics · Physics 2017-11-21 Domenico Ninno , Giovanni Cantele , Fabio Trani