Software projects

Free software

Both our WavePacket and Trajlab software projects are hosted at SourceForge, whereas WaveTrain is hosted at GitHub. These two platforms are leading in the development and distribution of free software, from where downloads of (current and previous) versions of the source codes as well as documentation, instructions, and support are available. In particular, our packages come with extended Wiki documentation. Even inexperienced users should be able to pursue their own simulation tasks within short time. Many worked-out examples illustrate the use of the WavePacket, WaveTrain, and TrajLab simulation tools, along with complete input and output files, partly also with (animated!) graphics. If you are interested, you are welcome to join the further development work.

WavePacket project

WavePacket is a program package for numerical simulation of quantum-mechanical wavepacket dynamics of distinguishable particles. It can be used to solve single or coupled time-independent or time-dependent (linear) Schrödinger and Liouville-von Neumann-equations, partly also classical or quantum-classical Liouville equations. Optionally accounting for the interaction with external electric fields within the semiclassical dipole approximation, WavePacket can be used to simulate modern experiments involving ultrashort light pulses in photo-induced physics or chemistry, including quantum optimal control. Allowing for easy visualization of quantum dynamics 'on the fly', WavePacket is suitable for teaching quantum mechanics as well as for research projects in physics and chemistry, see also the numerous demo examples that can be found on the associated Wiki pages.

Note that the main WavePacket project, as well as these two sub-projects, come with extensive Wiki documentation, see the hyperlinks above.

WaveTrain project

WaveTrain is an open-source software for numerical simulations of chain-like quantum systems with nearest-neighbor (NN) interactions only. (with or without periodic boundary conditions). This Python package is centered around tensor train (TT, or matrix product) representations of quantum-mechanical Hamiltonian operators and (stationary or time-evolving) state vectors. WaveTrain builds on the Python tensor train toolbox scikit_tt, which provides efficient construction methods, storage schemes, as well as solvers for eigenvalue problems and linear differential equations in the TT format.

WaveTrain comprises solvers for time-independent and time-dependent Schrödinger equations employing efficient decompositions to construct low-rank representations. Often, the tensor-train ranks of state vectors are found to depend only marginally on the chain length N, which results in the computational effort growing only slightly more than linearly in N, thus mitigating the curse of dimensionality. Thus, WaveTrain complements the existing WavePacket project at SourceForge which does not offer these advantages but which can be used for general Hamiltonians, i.e., without restriction to chain-like systems.

As a complement to the Python classes for full quantum mechanics, WaveTrain also contains classes for fully classical and mixed quantum-classical (Ehrenfest or mean field) dynamics of bipartite systems. The graphical capabilities allow visualization of quantum dynamics ‘on the fly’, with a choice of several different graphical representations based on reduced density matrices.

Available at GitHub since May 28, 2022

TrajLab project

TrajLab (still in beta-phase) is probably the first attempt for a general molecular simulation package in MATLAB. It is a set of three packages of MATLAB scripts serving the following purposes:

  • MolDynSim: classical molecular dynamics simulations based on (existing) force fields

  • MetaStable: metastability analysis of molecular conformations by adaptive clustering

  • MindStorms: demonstration experiments using LEGO MindStorms robots, see also here

While the authors are well aware that many other more specialized and/or highly optimized program packages for the same or similar purposes exist (e. g. AMBER, GROMACS, NAMD, etc.), the user-friendly MATLAB environment offers easy access to understanding and manipulating the codes, testing novel algorithms and non-standard force fields, advanced analysis techniques, and performing all kinds of numerical experiments with TrajLab. To be used mainly in teaching!