Damage monitoring in pipes and pressure vessels are important to ensure safety and reliability of these structures. Structural damage monitoring based on an actuator-sensor system is a promising technology to obtain real-time information for structural condition. Since piezoelectric materials in electromechanical systems can detect mechanical responses such stress and deformation as a sensor or perform a defined work as an actuator, piezoelectric actuators/sensors are extensively used in damage detection. In the design of piezoelectric actuators and sensors, it is important to know the properties of the piezoelectric material, in particular, piezoelectric constants to predict its actuation/sensing performance. In this study we determine a piezoelectric constant of ZnO using molecular dynamics simulations. We introduced a shell degree of freedom to the core-only atomic potential to enable polarization of the ion caused by an electric field. This modeling technique allowed for accurate piezoelectric response of the molecular structure.