: Identifying the stable structure of a system, is the first obligatory step for computation of it’s physical properties. Therefore structure search is a very important part of modern computational material science and is used for identifying the most stable structure of novel materials [Phys. Rev. Lett., vol. 109, 245503,2012], the novel phase of the existent materials [Science, vol. 342, 1502–5,2013], and the stable phase of material in the extreme conditions [Phys. Chem. Chem. Phys., vol. 15, 7696–700, 2013]. Finding the stable structures of tungsten oxide nano clusters is our aim in this thesis, first we introduce tungsten oxide and it’s various applications, and explain the Genetic Algorithm and USPEX program which is used for our structures search. We also discuss FHI-aims ab initio package which use Kohn-sham Density Functional Theory for electronic structure calculation and structure relaxation, and some explanation about interfacing of this code with USPEX will be given. Finally obtained stable structures of each cluster of tungsten oxide go under discussion and investigation of their stability, considering the criteria of relative energy, relative stability, formation energy and HOMO-LUMO gap, will be done.
