  Defects in graphene are both a boon and a bane for applications - they can
induce uncontrollable effects but can also provide novel ways to manipulate the
properties of pristine graphene. Nanoporous Graphene, which contains nanoscopic
holes, has found impactful applications in sustainability domains, e.g. gas
separation, water filtration membranes and battery technologies. For this
report, we investigate pore formation in graphene with no defect, one and two
mono-vacancies, and two di-vacancies using bespoke Dimensionally Restricted
Molecular Dynamics (DR-MD) designed for the purpose. We show DR-MD to be
superior to free-standing or substrate suspended configurations for simulating
stable defected structures. Applying DR-MD, stable pore configurations are
identified, and their formation mechanisms elucidated. We also investigated
formation mechanisms due to two Stone-Wales 55-77 defects, and the formation
energies of their linearly extended structures, along the zigzag and armchair
directions, and when they are placed in different relative orientations. This
study offers a way to identify stable porous defect structures in graphene and
insights into atomistic pore formation mechanisms for an environmentally
important material.
