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稀土化学研究一直是实验和理论化学家感兴趣的课题.理论计算由于必须考虑相对论效应和相关能校正而变得非常复杂,迄今为止对稀土化合物的精确理论计算还相当少.人们相继发展了多种相对论计算方法,其中相对论膺势法和相对论密度泛函方法是用于含重元素体系精确计算的最有效方法.密度泛函方法已成功地用于计算小分子、过渡金属络合物的结构常数、解离能、振动频率等性质,但还未用于稀土化合物的精确计算.我们用高精度的高斯数值积分方法和成熟的密度泛函非局域交换-相关势建立了一个非相对论与完全相对论密度泛函高精度计算程序(NR/R-DFT),并用Ziegler的广义过渡态法使总能量计算精度达到8位有效数字,满足一般量子化学计算的要求.本文报道EuO的理论势能曲线和由此得到的分子常数,并讨论相对论效应对分子常数的影响.
Rare earth chemistry has long been of interest to both experimental and theoretical chemists, and the theoretical calculations have become so complicated by the fact that relativistic effects and corrections must be taken into account. To date, precise theoretical calculations of rare earth compounds have been relatively rare. The theory of relativity, in which the relativistic method and the relativistic density functional method are the most effective methods for accurate calculation of heavy element-containing systems, has been successfully used to calculate the structure of small molecules, transition metal complexes Constants, dissociation energies, vibrational frequencies and other properties have not been used for the accurate calculation of rare earth compounds.We establish a non-relativistic and non-relativistic model with the high-precision Gaussian numerical integration method and the mature density functional non-local exchange-related potential Complete relativistic density functional high-precision calculation program (NR / R-DFT), and the total energy calculation accuracy of Ziegler’s generalized transition state method can reach 8 significant figures, which meets the requirements of general quantum chemistry calculation.The theoretical potential energy curve of EuO And the resulting molecular constants, and discuss the effects of relativistic effects on molecular constants.