利用UCCSD-FC方法研究PF^n(n=-1,0,+1)分子离子基态的势能函数

Study on the potential energy function for the ground state of the PF^n(n=-1,0,+1)molecule ion by UCCSD-FC method

基于Gaussian03程序包,利用UCCSD-FC方法,分别选用6-311G(df,pd)、6-311+G(df,pd)、6-311++G(2d,2p)、6-311++G(3d,3p)、6-31G(df,pd)、cc-PVDZ、D95基组对PF分子和PF^+、PF^-离子基态进行了几何优化,通过与实验值、理论值比较选出最优基组,进一步对其进行了频率计算和单点能扫描计算.用最小二乘法拟合得到了PF^n(n=-1,0,+1)分子离子基态的Murrell-Sorbie势能函数.与实验及理论结果比较表明,PF、PF^+分子离子基态光谱常数(B_e,a_e,ω_e,ω_ex_e)的计算结果达到了较高的精度.文章还首次给出PF^n(n=-1,0,+1)分子离子基态力常数(f_2,f_3,f_4)和PF^-离子基态光谱参数(B_e,a_e,ω_e,ω_ex_e)的理论数据,为PF^n(n=-1,0,+1)分子离子基态的后期研究提供重要的参考.研究表明PF^n(n=-1,0,+1)分子离子基态是稳定存在的,其稳定性次序为PF^+>PF>PF^-.

Based on the Gaussian03 calculation software, UCCSD-FC method has been used to optimize the possible ground-state structures of PF molecule and PF＋ .PF- molecule ion with the 6-311G（df, pd）.6-311＋G（df, pd）.6-311＋＋G（2d,2p）.6-311＋＋G（3d,3p）.6-31G（df, pd）.cc-PVDZ.D95 ba- sis sets respectively. Frequency and single-point energy scan for PFn（n=-1,0,＋1） have been calculated. Spectral parameters （Be,αe,ωe,ωex3） of the PF.PF＋ molecule ground state are obtained by least square fitting to the Murrell-Sorbie function, All calculation results are in good agreement with experimental data. In this work, spectral parameters （Be,αe,ωe,ωex3） Of PF- and force constants （ f2 ,f3 ,f4 ） of PF＇（n= --1,0, q-1） molecular ion for ground state are shown for the first time. This calculation may provide a good testing ground for investigation of PFn（n=-1,0,＋1） later. It shows that PFn（n=-1,0,＋1） molecular ion can be stable. Stability of the order of PF＋〉PF〉PF-.