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An efficient algorithm for time propagation of the time-dependent Kohn-Sham equations is presented. The algorithm is based on dividing the Hamiltonian into small time steps and assuming that it is constant over these steps. This allows for…

Computational Physics · Physics 2014-12-03 J. K. Dewhurst , K. Krieger , S. Sharma , E. K. U. Gross

The goal of this project is to compare the performance of exponential time integrators with traditional methods such as diagonally implicit Runge-Kutta methods in the context of solving the system of reduced magnetohydrodynamics (RMHD). In…

Numerical Analysis · Mathematics 2022-07-07 Valentin Dallerit , Mayya Tokman , Ilon Joseph

We compare exponential-type integrators for the numerical time-propagation of the equations of motion arising in the multi-configuration time-dependent Hartree-Fock method for the approximation of the high-dimensional multi-particle…

Numerical Analysis · Mathematics 2019-05-15 Winfried Auzinger , Alexander Grosz , Harald Hofstätter , Othmar Koch

Simulating electron-ion dynamics using time-dependent density functional theory within an Ehrenfest dynamics scheme can be done in two ways that are in principle exact and identical: propagating time-dependent electronic Kohn-Sham equations…

Chemical Physics · Physics 2021-07-01 Lionel Lacombe , Neepa T. Maitra

We examine various integration schemes for the time-dependent Kohn-Sham equations. Contrary to the time-dependent Schr\"odinger's equation, this set of equations is non-linear, due to the dependence of the Hamiltonian on the electronic…

Computational Physics · Physics 2018-03-07 Adrián Gómez Pueyo , Miguel A. L. Marques , Angel Rubio , Alberto Castro

In this work, the existence, uniqueness and regularity of solutions to the time-dependent Kohn-Sham equations are investigated. The Kohn-Sham equations are a system of nonlinear coupled Schr\"odinger equations that describe multi-particle…

Analysis of PDEs · Mathematics 2018-03-14 Martin Sprengel , Gabriele Ciaramella , Alfio Borzì

Time-dependent density-functional theory (TDDFT) is a computationally efficient first-principles approach for calculating optical spectra in insulators and semiconductors, including excitonic effects. We show how exciton wave functions can…

Materials Science · Physics 2020-12-29 Jared R. Williams , Nicolas Tancogne-Dejean , Carsten A. Ullrich

With growing demand for time-domain simulations of correlated many-body systems, the development of efficient and stable integration schemes for the time-dependent Schr\"odinger equation is of keen interest in modern electronic structure…

Chemical Physics · Physics 2023-08-22 David B. Williams-Young , Stephen Yuwono , A. Eugene DePrince , Chao Yang

The objective of this work is the introduction and investigation of favourable time integration methods for the Gross--Pitaevskii equation with rotation term. Employing a reformulation in rotating Lagrangian coordinates, the equation takes…

Numerical Analysis · Mathematics 2019-10-29 Philipp Bader , Sergio Blanes , Fernando Casas , Mechthild Thalhammer

This paper is devoted to the construction of exponential integrators of first and second order for the time discretization of constrained parabolic systems. For this extend, we combine well-known exponential integrators for unconstrained…

Numerical Analysis · Mathematics 2019-07-08 Robert Altmann , Christoph Zimmer

A fundamental task in particle-in-cell (PIC) simulations of plasma physics is solving for charged particle motion in electromagnetic fields. This problem is especially challenging when the plasma is strongly magnetized due to numerical…

Computational Physics · Physics 2026-01-01 Tri P. Nguyen , Ilon Joseph , Mayya Tokman

We present a class of exponential integrators to compute solutions of the stochastic Schr\"odinger equation arising from the modeling of open quantum systems. In order to be able to implement the methods within the same framework as the…

Computational Physics · Physics 2020-02-05 Jingze Li , Xiantao Li

The implementation of the discrete adjoint method for exponential time differencing (ETD) schemes is considered. This is important for parameter estimation problems that are constrained by stiff time-dependent PDEs when the discretized PDE…

Optimization and Control · Mathematics 2016-10-11 Kai Rothauge , Eldad Haber , Uri Ascher

Exponential integrators are special time discretization methods where the traditional linear system solves used by implicit schemes are replaced with computing the action of matrix exponential-like functions on a vector. A very general…

Numerical Analysis · Computer Science 2017-01-26 Mahesh Narayanamurthi , Paul Tranquilli , Adrian Sandu , Mayya Tokman

This paper deals with the application of probabilistic time integration methods to semi-explicit partial differential-algebraic equations of parabolic type and its semi-discrete counterparts, namely semi-explicit differential-algebraic…

Numerical Analysis · Mathematics 2024-12-02 R. Altmann , A. Moradi

Allowing for space- and time-dependence of mass in Klein--Gordon equations resolves the problem of negative probability density and of violation of Lorenz covariance of interaction in quantum mechanics. Moreover it extends their…

Numerical Analysis · Mathematics 2023-07-03 Karolina Kropielnicka , Karolina Lademann

Exponential integrators have been introduced as an efficient alternative to explicit and implicit methods for integrating large stiff systems of differential equations. Over the past decades these methods have been studied theoretically and…

Numerical Analysis · Mathematics 2018-04-03 Lukas Einkemmer , Mayya Tokman , John Loffeld

Given the time-evolution of an electron charge density, the local potential in Kohn-Sham time-dependent density functional theory (KS-TDDFT) can be modeled as a sum of instantaneous and dynamic contributions by assuming a certain form of…

Computational Physics · Physics 2016-11-09 R. J. Magyar

In this paper, we implement exponential integrators, specifically Integrating Factor (IF) and Exponential Time Differencing (ETD) methods, using pseudo-spectral techniques to solve phase-field equations within a Python framework. These…

Numerical Analysis · Mathematics 2023-05-17 Elvis do A. Soares , Amaro G. Barreto , Frederico W. Tavares

Exponential time differencing methods is a power tool for high-performance numerical simulation of computationally challenging problems in condensed matter physics, fluid dynamics, chemical and biological physics, where mathematical models…

Numerical Analysis · Mathematics 2024-10-15 Evelina V. Permyakova , Denis S. Goldobin
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