NX(X=F,Cl,Br)分子结构与极化函数f轨道的作用

用密度泛函理论的Becke3LYP方法，计算了NX（X=F，Cl,Br）的激发态b1Σ＋ 和基态X3Σ－，并对比不含f轨道的基集合cc-pvDZ和6-311＋G与含f轨道的基集合6-311＋G(3df)的计算结果，发现极化函数f轨道对NCl和NBr的键长与谐振频率ωe有明显改进作用，即f轨道对成键有贡献，而f轨道对NF的Re和ωe则无明显作用.同时，基于能量共振转移的需要，用NF代替O2-I 红外激光系统的O2是不适宜的，而用NCl和NBr代替则是可能的.

Molecular Structure for NX(X=F,Cl,Br) and the Contribution of Polarization Functions f Orbitals

Excited states b1Σ＋ and ground states X3Σ－ for molecules NX(X=F,Cl,Br) have been calculated using density functional theory(DFT) Becke 3LYP.In comparison of the calculated results with f orbitals basis set 6-311＋G(3df) and that without f orbitals basis sets cc-pvDZ and 6-311＋G,it is instructive to notice that the polarization function f orbitals significantly contribute to improve in bond lengths Re and vibration frequencies ωe for NCl and NBr,but not for NF.Therefore,the f orbitals not only play some subtle aspects in bonding for lanthanides and actinides,but also for the elements lighter than lanthanum.