A new generation density functional towards chemical accuracy

Abstract: Density functional theory (DFT) has become the leading method in calculating theelectronic structures and properties from first principles. In practical applicationsof DFT in the frame work of Kohn-Sham (KS) method, an approximate exchange-correlation functional has to be chosen. Hence, the success of a DFT calculationcritically depends on the quality of the exchange-correlation functional.This thesis focuses on the development and validation of the so-called dou-bly hybrid density functionals (DHDFs). DHDFs present a new generation offunctionals, which not only have a non-local orbital-dependent component in theexchange part, but also incorporate the information of unoccupied orbitals in thecorrelation part. I will first give an overview of modern DFT in the introductorychapters, emphasizing the theoretical bases of a newly developed DHDF, XYG3.I will then present further examination of XYG3 and new development on top ofXYG3, leading to XYG3o and XYG3s. Attempts have also been made to extractband structure information of a periodic system from cluster model calculations.