Optical Properties of the Most Stable GaxPy (x+y=2 to 5) Nanoclusters predicted through First Principles

A TDDFT study has been performed for the optical properties of the most stable Ga _x P _y (x + y = 2 to 5) nanoclusters. A B3LYP-DFT/6-31G(d) method is employed to optimize the geometries of GaP nanoclusters and a TDDFT method is used for the study of optical properties of the most stable structures of individual configurations. The zero-point energy correction is also considered in this study. The structure having minimum energy in evaluation to other structures for the same values of “x” and “y” is considered as the most stable one. Some of the nanoclusters show at least one imaginary vibrational frequency, which consequences to their instability. Almost all the nanoclusters show strong absorption in the ultraviolet region or the extreme ultraviolet region. Some nanoclusters show appreciable absorption in the visible region. These investigations reveal that in most of the nanoclusters; the absorption is obtained in the lower energy side in Ga-rich nanoclusters and on the higher energy side in P-rich nanoclusters. The development of these most stable nanoclusters may be possible in the experiments.