Assessment on The Accuracy of Piezoelectric Property Calculations of Single Layer Two Dimensional Hexagonal Crystals

Abstract

The finite difference and the density functional perturbation theory based piezoelectric property calculation methods are applied to the novel two dimensional hexagonal materials named as group II-VI monolayers and transition metal dichalcogenides for the purposes of comparison. The clamped- and relaxed- ion coefficients have been calculated separately to test the accuracy of both methods on electronic and ionic piezoelectric response contributions. While there is no significant difference between the clamped-ion piezoelectric coefficients calculated with these two methods, a notable difference between the values for relaxed-ion piezoelectric coefficients are determined. Considering the results of the density functional perturbation theory given in the previous applications, it has been determined that the consistency of the finite difference method in the ionic contribution calculation do not provide reliable results for some 2D materials. We have predicted that the atomic relaxation for different strain values is not adequate to achieve accurate results for ionic contribution of piezoelectric coefficient. However, on the contrary to the explicit difference in the coefficients calculated with two different approaches, our results clearly show that the piezoelectric potentials of the considered materials can be determined accurately and reliably by both methods.