  The phase-field crystal model (PFC) describes crystal structures at diffusive
timescales through a periodic order parameter representing the atomic density.
One of its main features is that it naturally incorporates elastic and plastic
deformation. To correctly interpret numerical simulation results or devise
extensions related to the elasticity description, it is important to have
direct access to the elastic field. In this work, we discuss its evaluation in
classical PFC models based on the Swift-Hohenberg energy functional. We
consider approaches where the stress field can be derived from the microscopic
density field (i.e., the order parameter), and a simple novel numerical routine
is proposed. By numerical simulations, we demonstrate that it overcomes some
limitations of currently used methods. Moreover, we shed light on the
elasticity description conveyed by classical PFC models, characterizing a
residual stress effect present at equilibrium. We show explicitly and discuss
the evaluation of the elastic fields in prototypical representative cases
involving an elastic inclusion, a grain boundary, and dislocations.
