  A computational method is developed for the study of mechanical response and
fracture behavior of phase field crystals (PFC), to overcome a limitation of
the PFC dynamics which lacks an effective mechanism for describing fast
mechanical relaxation of the material system. The method is based on a simple
interpolation scheme for PFC (IPFC) making use of a condition of the
displacement field to satisfy local elastic equilibration, while preserving key
characteristics of the original PFC model. We conduct a systematic study on the
mechanical properties of a sample nanoribbon system with honeycomb lattice
symmetry subjected to uniaxial tension, for numerical validation of the IPFC
scheme and the comparison with the original PFC and modified PFC methods.
Results of mechanical response, in both elasticity and fracture regimes, show
the advantage and efficiency of the IPFC method across different system sizes
and applied strain rates, due to its effective process of mechanical
equilibration. A brittle fracture behavior is obtained in IPFC calculations,
where effects of system temperature and chirality on the fracture strength and
Young's modulus are also identified, with results agreeing with those found in
previous atomistic simulations of graphene. The IPFC scheme developed here is
generic and applicable to the mechanical studies using different types of PFC
free energy functionals designed for various material systems.
