Random explorations of material structure spaces

CCMMP Seminars
Chris Pickard
Alston Misquitta
November 24th, 2015 at 14:00
GO Jones Room 610

The use of stochastic optimisation strategies to identify low energy configurations in the first principles energy landscape of collections of atoms is now well established. The methods used are diverse, and sometimes rather complex. Ab Initio Random Structure Searching (AIRSS), [1,2] in which initial starting structures are randomly generated (with varying degrees of preparation) and relaxed to the nearest local energy minimum repeatedly, is extremely simple and reliable. There are now many examples of these techniques making genuine computational, and scientific, discoveries, particularly in the field of high-pressure physics. However, high-pressure studies are extremely challenging experimentally, and tend to focus on relatively simple chemical systems. Computational investigations of the binary compounds frequently overlook the key compositions. Many functional materials are ternary, quaternary, or higher, compounds. It is important to perform the search over compositional space as thoroughly (for each composition) and broadly (over compositions) as possible. I will discuss how AIRSS may be used to do this, paying particular attention to pulling apart structures we have already found, to make new, random ones.

[1] C.J. Pickard and R.J. Needs, Phys. Rev. Lett. 2006, 97, 45504
[2] C.J. Pickard and R.J. Needs, J. Phys.: Condens. Matter Topical Review 2011, 23, 053201