Energy Landscape Investigations Using the Prescribed Path Method in the ZnO System

An important issue in modern solid-state chemistry and nanotechnology is the development of a general methodology to predict possible (meta)stable crystalline and nanocrystalline modifications and to study the possible transition routes among them. To analyze the stability of the various potential modifications and study the possible low energy paths among them, the so-called prescribed path method is employed. This method allows us to explore transition routes and barriers between even distant minima, suggesting possible transition states and specific transition paths for more detailed analysis, as well as to gain more insights into the temperature dependence of the synthesis and transformation processes in the system. In this study, we describe and employ the prescribed path method for the example of the energy landscape of ZnO. The focus is on the influence of the temperature on the transformations along the path and on the stability of the various structures in the ZnO system, such as the wurtzite-, the sphalerite-, and the rock salt-type modifications. The results of our calculations are in good agreement with the experimental data, and we suggest several possible transition states such as the 5-5 and the GeP type along the B4-B1 transition path in agreement with previous calculations. This approach of analyzing transition route bundles among (predicted) modifications could be especially important for growing and eventually controlling synthesis and transformation of metastable nanocrystalline zinc oxide.