Local structure and dynamics of wurtzite-type ZNO from simulation-based EXAFS analysis

Abstract

Conventional methods of EXAFS data analysis are often limited to the nearest coordination shells of the absorbing atom due to the difficulties in accurate accounting for the so-called multiple-scattering effects. Besides, it is often difficult to resolve the non-equivalent groups of atoms in a single coordination shell due to strong correlation between structural parameters. In this study we overcome these problems by applying two different simulation-based methods, i.e., classical molecular dynamics (MD) and reverse Monte Carlo (RMC) coupled with evolutionary algorithm (EA), to the analysis of the Zn K-edge EXAFS data for wurtzite-type bulk ZnO. The RMC/EA-EXAFS method allowed us to separate the contributions of thermal disorder and the effect of noncentrosymmetric zinc oxide structure, being responsible for its piezoelectrical and pyroelectrical properties. The MD-EXAFS method allowed us to test the accuracy of several available force-field models, which are commonly used in the MD simulations of ZnO nanostructures.