  Fueled by advances in hardware and algorithm design, large-scale automated
explorations of chemical reaction space have become possible. Here, we present
our approach to an open-source, extensible framework for explorations of
chemical reaction mechanisms based on the first principles of quantum
mechanics. It is intended to facilitate reaction network explorations for
diverse chemical problems with a wide range of goals such as mechanism
elucidation, reaction path optimization, retrosynthetic path validation,
reagent design, and microkinetic modeling. The stringent first-principles basis
of all algorithms in our framework is key for the general applicability that
avoids any restrictions to specific chemical systems. Such an agile framework
requires multiple specialized software components of which we present three
modules in this work. The key module, Chemoton,drives the exploration of
reaction networks. For the exploration itself, we introduce two new algorithms
for elementary-step searches that are based on Newton trajectories. The
performance of these algorithms is assessed for a variety of reactions
characterized by a broad chemical diversity in terms of bonding patterns and
chemical elements. We reproduce and significantly extend what is known about
these reactions and provide the resulting data to be used as a starting point
for further explorations and for future reference.
