Abstract:

Different quantum chemical ab initio methods and basis sets were adopted to investigate the structures and second-order nonlinear optical properties of H₃PAuR type mononuclear Au(Ⅰ) complexes. The influence of different calculation methods and basis sets of Au on the calculation results were also discussed systematically. The results indicate that different methods give rise to a great effect on the structures and secondorder nonlinear optical properties of mononuclear Au(Ⅰ) complexes. Herein, the length of coordinative bond of Au—P from HF method is shorter than that from DFT B3LYP and MP2 methods. Moreover, the second-order NLO coefficients obtained by DFT B3LYP and MP2 methods are two times larger than that by HF method. Based on the same methods, the coordinative bond length of Au—P decreased with increasing the number of d orbitals in the basis set of Au. Meanwhile, with increasing the basis sets of Au, the energy gap of frontier molecular orbitals decreased, which can be observed clearly for the SDD and CEP-121G basis sets. However, different basis sets have little influence on the second-order NLO coefficients. The difference of β_μ value with different basis sets of Au for most of the molecules is less than 10%.

Key words: Mononuclear Au(Ⅰ) complex, Calculation method and basis set, Structure, Secondorder NLO coefficient