This book takes an altogether unique approach to GaAs clusters providing in-depth different isomers of GaAs clusters. It provides information about the minimum energy of the isomers, electronic properties and the optical characteristics. The upshot of the work agree theoretically and experimentally with most of the works done before. We have tried to revise others' related works, as it is written in the book. And it provides information for those who want to study GaAs clusters for different electronic and optical purpose on theoretical and experimental basis. The many helpful features of GaAs clusters include Binding energy of different Isomers of GaAs clusters. Bond length of different Isomers of GaAs clusters. Band-gap energy of different isomers of GaAs clusters. Optical properties of the most stable structure of GaAs cluster. Numerous figures and tables to clarify electronic and optical properties of GaAs clusters. Over hundred illustrations of the clusters are provided.