中文摘要：

用密度泛函理论方法研究了镥二聚体（Lu2）低能量电子态的性质，计算了电子态相对能量、平衡键长、振动频率以及基态解离能，考察了密度泛函性质、相对论有效势种类以及Hartree—Fock交换作用大小对计算结果的影响．结果表明，无论采用何种密度泛函和相对论有效势，体系的基态都为三重态，与其他一些基于分子轨道理论的从头计算方法得到的结论是一致的．另外，与分子轨道从头计算结果以及实验结果比较发现，采用杂化密度泛函理论和Stuttgart小核有效势计算得到的结果总体吻合最好．最后，特别分析研究了B3LYP计算中Hartree—Fock交换作用大小对基态键长和基态解离能的影响，发现随着交换作用的增大，键长增长，解离能减小，这是由于5d轨道杂化导致的共价成键作用减弱造成的．

英文摘要：

Low-lying electronic states of the lutetium dimer （Lu2） were studied based on density functional theory （DFT） using ten different density functionals together with three different relativistic effective core pseudopotentials （RECPs）. Relative state energies, equilibrium bond lengths, vibrational frequencies, and ground-state dissociation energies were evaluated. It was found that the ground state is a triplet state irrespective of the type of functional and RECP used. This result is in contrast with a previous DFT calculation which gave a singlet ground state for Lu2. By comparing with the high-level ab initio and available experimental results, it is evident that the hybrid-GGA functionals combined with the Stuttgart smallcore RECP yield the best overall agreement for the properties under study. The effects of Hartree-Fock exchange in B3LYP functional on the calculated bond length and dissociation energy of the ground state were examined, and rationalized in terms of 5d participation in Lu-Lu covalent bonding.