We report implementation of a hierarchical equations of motion (HEOM)
module within the open-source Libra software. It includes the standard
and scaled HEOM algorithms for computing the dynamics of open quantum
systems interacting with a harmonic bath. The module allows computing
evolution of the reduced density matrix as well as spectral lineshapes.
The truncation, filtering, and “update list” schemes as well as OpenMP
parallelization allow for further computational saving. The package is
written in a mix of C++ and Python languages, delivering the best
compromise between user friendliness and efficiency. The Python layer of
the package takes advantage of standard Python libraries, such as h5py
which allows efficient storage and retrieval of the generated results.
The package can be seamlessly used within Jupyter notebooks; its careful
design shall provide the maximal convenience and intuitiveness to its