PNNL

Abstract

A brief review of electronic structure methods used to calculate the properties of self-trapped excitons in silica is presented. The computational focus has been on silica crystalline systems because amorphous systems, such as fused silica, pose a significant technical challenge. The tremendous growth in speed of computer processors and available memory has led to a new generation of ab initio computer codes capable of carrying out extensive calculations. The capabilities in these codes has also grown with regards to the sophistication of both basis sets, for wave function based methods, and pseudopotentials, for density functional methods. In particular, these codes have made calculations of excited states more accessible. The growth in the sophistication of calculations is presented along with modern capabilities that include preliminary studies of self-trapped excitons at surfaces and in amorphous structures. Previous ab initio calculations have been repeated with larger basis sets and more accurate calculation methods. The new results agree nicely with experimental results, thus further legitimizing the original predictions. Recent results also predict the presence of multiple STEs that may have connective paths between them.