  Numerical simulations are a powerful tool to study quantum systems beyond
exactly solvable systems lacking an analytic expression. For one-dimensional
entangled quantum systems, tensor network methods, amongst them Matrix Product
States (MPSs), have attracted interest from different fields of quantum physics
ranging from solid state systems to quantum simulators and quantum computing.
Our open source MPS code provides the community with a toolset to analyze the
statics and dynamics of one-dimensional quantum systems. Here, we present our
open source library, Open Source Matrix Product States (OSMPS), of MPS methods
implemented in Python and Fortran2003. The library includes tools for ground
state calculation and excited states via the variational ansatz. We also
support ground states for infinite systems with translational invariance.
Dynamics are simulated with different algorithms, including three algorithms
with support for long-range interactions. Convenient features include built-in
support for fermionic systems and number conservation with rotational
$\mathcal{U}(1)$ and discrete $\mathbb{Z}_2$ symmetries for finite systems, as
well as data parallelism with MPI. We explain the principles and techniques
used in this library along with examples of how to efficiently use the general
interfaces to analyze the Ising and Bose-Hubbard models. This description
includes the preparation of simulations as well as dispatching and
post-processing of them.
