eTraj.jl: Trajectory-based simulation for strong-field ionization

IF 7.2 2区物理与天体物理 Q1 COMPUTER SCIENCE, INTERDISCIPLINARY APPLICATIONS

Computer Physics Communications Pub Date : 2025-02-20 DOI:10.1016/j.cpc.2025.109549

Mingyu Zhu , Hongcheng Ni , Jian Wu

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引用次数: 0

Abstract

The dynamics of light-matter interactions in the realm of strong-field ionization has been a focal point and has attracted widespread interest. We present the eTraj.jl program package, designed to implement established classical/semiclassical trajectory-based methods to determine the photoelectron momentum distribution resulting from strong-field ionization of both atoms and molecules. The program operates within a unified theoretical framework that separates the trajectory-based computation into two stages: initial-condition preparation and trajectory evolution. For initial-condition preparation, we provide several methods, including the Strong-Field Approximation with Saddle-Point Approximation (SFA-SPA), SFA-SPA with Non-adiabatic Expansion (SFA-SPANE), and the Ammosov-Delone-Krainov theory (ADK), with atomic and molecular variants, as well as the Weak-Field Asymptotic Theory (WFAT) for molecules. For trajectory evolution, available options are Classical Trajectory Monte-Carlo (CTMC), which employs purely classical electron trajectories, and the Quantum Trajectory Monte-Carlo (QTMC) and Semi-Classical Two-Step model (SCTS), which include the quantum phase during trajectory evolution. The program is a versatile, efficient, flexible, and out-of-the-box solution for trajectory-based simulations for strong-field ionization. It is designed with user-friendliness in mind and is expected to serve as a valuable and powerful tool for the community of strong-field physics.

Program summary

Program title: eTraj.jl

CPC Library link to program files: https://doi.org/10.17632/33fm297cz4.1

Developer's repository link: https://github.com/TheStarAlight/eTraj.jl

Licensing provisions: Apache-2.0

Programming language: Julia

Nature of problem: Atoms and molecules exposed in an intense laser field go through complex processes of ionization through mechanisms such as multi-photon ionization and tunneling ionization. The trajectory-based methods are powerful tools for simulating these processes, and have considerable advantages over the time-dependent Schrödinger equation (TDSE) and the strong-field approximation (SFA). However, the community lacks a unified theoretical framework for trajectory-based methods, and there are no public-available code that implements the schemes.

Solution method: We developed a general, efficient, flexible, and out-of-the-box solution for trajectory-based simulation program named after eTraj.jl using the Julia programming language. This program conducts trajectory-based classical/semiclassical simulations of photoelectron dynamics under the single-active-electron approximation and the Born-Oppenheimer approximation. It supports multiple methods, including the SFA-SPA, SFA-SPANE, ADK and WFAT for initial condition preparation. Additionally, it incorporates the CTMC, QTMC and SCTS methods for trajectory evolution. The program is written in a clear and concise manner, and features versatility, extensibility, and usability.

Additional comments including restrictions and unusual features: A detailed documentation is available at https://thestaralight.github.io/eTraj.jl/stable/. The package has been tested for compatibility with Julia versions 1.9 to 1.11 and is expected to remain compatible with newer Julia versions released after the test date.

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eTraj。[j]：基于轨迹的强场电离模拟

在强场电离领域，光-物质相互作用的动力学一直是一个焦点，并引起了广泛的兴趣。我们介绍eTraj。Jl程序包，旨在实现已建立的基于经典/半经典轨迹的方法，以确定原子和分子的强场电离引起的光电子动量分布。该程序在统一的理论框架内运行，该框架将基于轨迹的计算分为两个阶段：初始条件准备和轨迹演化。对于初始条件的制备，我们提供了几种方法，包括具有鞍点近似的强场近似（SFA-SPA），具有非绝热膨胀的SFA-SPA (SFA-SPANE)，具有原子和分子变体的Ammosov-Delone-Krainov理论（ADK），以及分子的弱场渐近理论（WFAT）。对于轨迹演化，可用的选择是经典轨迹蒙特卡罗（CTMC），它采用纯经典电子轨迹，以及量子轨迹蒙特卡罗（QTMC）和半经典两步模型（SCTS），其中包括轨迹演化过程中的量子相。该程序是一个通用的、高效的、灵活的、开箱即用的解决方案，用于基于轨迹的强场电离模拟。它的设计考虑到用户友好性，并有望成为强场物理社区的一个有价值和强大的工具。节目简介节目名称：eTraj。jlCPC库链接到程序文件：https://doi.org/10.17632/33fm297cz4.1Developer's存储库链接：https://github.com/TheStarAlight/eTraj.jlLicensing条款：apache -2.0编程语言：julia问题的性质：暴露在强激光场中的原子和分子通过多光子电离和隧道电离等机制经历复杂的电离过程。基于轨迹的方法是模拟这些过程的强大工具，与时间相关的Schrödinger方程（TDSE）和强场近似（SFA）相比具有相当大的优势。然而，社区缺乏基于轨迹的方法的统一理论框架，并且没有实现这些方案的公开可用代码。求解方法：我们开发了一个通用的、高效的、灵活的、开箱即用的基于轨迹的仿真程序，命名为eTraj。使用Julia编程语言编写。该程序在单活性电子近似和Born-Oppenheimer近似下进行基于轨迹的光电子动力学经典/半经典模拟。它支持多种初始条件制备方法，包括SFA-SPA、SFA-SPANE、ADK和WFAT。此外，它还结合了CTMC、QTMC和SCTS方法进行轨迹演化。该程序以清晰简洁的方式编写，具有多功能性，可扩展性和可用性。其他评论，包括限制和不寻常的功能：详细的文档可在https://thestaralight.github.io/eTraj.jl/stable/上获得。该包已经测试了与Julia 1.9到1.11版本的兼容性，并且预计将与测试日期之后发布的新Julia版本保持兼容。

本文章由计算机程序翻译，如有差异，请以英文原文为准。

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来源期刊

Computer Physics Communications 物理-计算机：跨学科应用

CiteScore

12.10

自引率

3.20%

发文量

287

审稿时长

5.3 months

期刊介绍： The focus of CPC is on contemporary computational methods and techniques and their implementation, the effectiveness of which will normally be evidenced by the author(s) within the context of a substantive problem in physics. Within this setting CPC publishes two types of paper. Computer Programs in Physics (CPiP) These papers describe significant computer programs to be archived in the CPC Program Library which is held in the Mendeley Data repository. The submitted software must be covered by an approved open source licence. Papers and associated computer programs that address a problem of contemporary interest in physics that cannot be solved by current software are particularly encouraged. Computational Physics Papers (CP) These are research papers in, but are not limited to, the following themes across computational physics and related disciplines. mathematical and numerical methods and algorithms; computational models including those associated with the design, control and analysis of experiments; and algebraic computation. Each will normally include software implementation and performance details. The software implementation should, ideally, be available via GitHub, Zenodo or an institutional repository.In addition, research papers on the impact of advanced computer architecture and special purpose computers on computing in the physical sciences and software topics related to, and of importance in, the physical sciences may be considered.