Energy-Band Structure of Selenium Chains

The tight-binding method is applied to the valence and lowest conduction bands of selenium chains. Essentially, the calculations of Reitz have been extended and made quantitative. The general features of his results have been verified, a fact which is of interest because in recent years several variants of his band structure have been proposed. However, in detail, our results are quite different; for example, we find that s-p mixing has a nonnegligible effect. With only slight modification, our computed energy bands for chains are found to be successful in interpreting many details appearing in recent reflectivity data on crystalline selenium.