Development and applications of relativistic correlation consistent basis sets for lanthanide elements and accurate ab initio thermochemistry and spectroscopy
The relativistic correlation consistent basis sets for Lanthanide elements are developed with the 3rd-order Douglas-Kroll-Hess Hamiltonian. Atomic and molecular benchmark calculations show robust reliability of the new basis sets. Applications based on the new sets were performed, which include correcting the dissociation energy of the LuF molecule, resolving the geometry controversy of the LnX3 molecules (Ln= La, Nd, Gd, Dy, Lu; X=F, Cl, Br) and predicting the new molecules of isoelectronic to the Gd2 molecule. Spectroscopy studies of coinage metal nitroxyl molecules as well as CCX (X=P, As) radicals are also performed. The calculations should provide the most accurate theoretical results up to date. The first chapter of this dissertation briefly introduces the motivation and background of studied projects. Chapter 2 offers a summarization of the computational methods used in the study. Chapter 3 to chapter 7 present details of the studied projects.