Udkm1Dsim – a Python toolbox for simulating 1D ultrafast dynamics in condensed matter

Abstract

The udkm1Dsim toolbox is a collection of Python classes and routines to simulate the thermal, structural, and magnetic dynamics after laser excitation as well as the corresponding X-ray scattering response in one-dimensional samples, such as multilayers. The toolbox provides the capabilities to define arbitrary layered structures on the atomic level including a rich database of element-specific physical properties. The excitation of dynamics is represented by an N-temperature-model which is commonly applied in ultrafast physics. Structural dynamics due to thermal stresses are calculated by a linear-chain model of masses and springs. The implementation of specific magnetic dynamics can be easily accomplished by the user employing a generalized magnetization interface class. The resulting X-ray diffraction response is computed by kinematical or dynamical X-ray theory which can also include polarization-dependent magnetic scattering. The udkm1Dsim toolbox is highly modular and allows for injecting user-defined inputs at any step within the simulation procedure. New version program summaryProgram Title: udkm1DsimCPC Library link to program files:https://doi.org/10.17632/bnzw823v6y.1Developer's repository link:https://github.com/dschick/udkm1DsimCode Ocean capsule:https://codeocean.com/capsule/8131941Licensing provisions: MITProgramming language: PythonJournal reference of previous version: Comput. Phys. Commun. 185 (2) (February 2014) 651–660Does the new version supersede the previous version?: YesReasons for the new version: The toolbox has been ported from MATLAB (MathWorks Inc.) to Python and is based exclusively on free and open-source components. Moreover, new features have been added that allow for a broader applicability of the toolbox.Summary of revisions: Porting to Python.Introduction of amorphous layers in the sample structures.Add magnetization property to atoms and layers.Multilayer formalism to calculate laser absorption.New magnetization class to allow for user-defined magnetization dynamics.New resonant magnetic X-ray scattering employing dynamical X-ray theory.Calculation of X-ray scattering as function of photon energy and scattering vector.Nature of problem: Simulate the thermal, structural, and magnetic dynamics of 1D layered sample structures due to an ultrafast laser excitation and compute the corresponding transient (magnetic) X-ray scattering response.Solution method: The program provides an object-oriented toolbox for building arbitrary layered 1D crystalline/amorphous sample structures including a rich database of element-specific parameters. The excitation, thermal transport, and lattice dynamics are simulated utilizing SciPy's ODE solver. Magnetization dynamics can be introduced by the user employing a magnetization interface class. The dynamical (magnetic) X-ray scattering is computed by a matrix formalism that can be parallelized.Additional comments including restrictions and unusual features: The program is restricted to 1D layered sample structures. Phonon dynamics only include longitudinal acoustic phonons (sound waves). Magnetization dynamics have to be defined by the user. X-ray scattering only allows for symmetrical and co-planar geometries due to the 1D nature of the toolbox. The program is highly modular and allows the inclusion of user-defined inputs at any time of the simulation procedure.