Provided you have a suitable bulk structure of the Ta2O5 (like discussed in
Journal of Applied Physics, AIP, 106, 103713 (2009)), you can use the "Builder 2012" in VNL 11.8 to cleave the structure, there is a new and improved Surface Builder in this tool. You can download a time-limited beta-version of 11.8 from our website, it works with the older 11.2 license.
The "Builder 2012" in 11.8 is a preview version of the ultimate new Builder that will be presented in 12.2, with lots of new functionality.