<title>Quantum mechanical characterization of the microscopic structure and nonlinear optical properties of radiation-induced defects in a-SiO2</title>

Structure and Nonlinear Optical Properties of Cationic Defects in Amorphous Silicon Dioxide. 1. Cluster Studies

“…In this paper we present the results of our study of the effect on the local geometry and microscopic nonlinear optical properties of the oxide network in the presence of positively charged ions. While neutral point defects, such as the 3-fold coordinated Si/Ge atom, peroxy linkage, and atomic H , also constitute the family of point defects found in amorphous silica, it is generally believed that the SHG in these materials involves space charge field created by positively charged species. − Furthermore, in a previous ab initio TDHF calculation it was shown that the presence of a proton (H + ) around a SiO 2 cluster in oxide network substantially changes the value of the second-order NLO coefficient . Therefore, the current study focuses on the effect of several positively charged species, H + , Li + , Be 2+ , Na + , and Mg 2+ , on the structure and microscopic NLO properties of the oxide network.…”