摘要
应用密度泛函理论的B3LYP方法和6-311++g(d,p)基组,研究Li_2、Li S和Li_2S分子的基态构型.结果表明它们的基电子态分别为X^1Σ_g^+、X^2Π和X^1Σ_g^+.通过非线性曲线拟合,得到基态Li S和Li_2分子的4参数MurrellSorbie分析势能函数,计算它们的光谱参数和力常数.基于多体项展式理论得到了基态Li_2S分子的单重态势能面的分析函数.利用得到的分析势能函数重构基态单重Li_2S分子的旋转图、伸缩图和旋转伸缩图,准确地再现了Li_2S分子的静态特征,如平衡结构,最低能量,合理反应通道.从等值势能面图看出,反应Li+S+Li→Li_2S是一个无阈值反应.S原子攻击Li_2分子的反应通道上,有一个过渡态.Li原子攻击Li S分子通道上也有一个过渡态.
Structures of ground states of Li2 , LiS and Li2 S molecules are investigated using density function theory B3LYP method and 6-311＋＋g（ d,p） basis set. It shows that their electronic states are X1Σg＋, X2Πg and X1Σg＋. Murrell-Sorbie potential functions with 4 parameters for LiS and Li2 molecules are obtained with nonlinear curve fitting method. Spectral parameters and force constants are studied with Murrel-Sobie potential functions. Analytical potential surface of singlet Li2 S is obtained with many-body expansion theory. Rotary contour map, stretching contour map and rotary stretching contour map are reconstructed with analytical potential surface. Static characters of ground singlet Li2 S are repeated exactly through these maps. They are equilibrium geometric structure, lowest energy and reasonable chemical reaction channels, respectively. Stretching vibrational contours of potential energy surface show that reaction Li＋S＋Li→Li2 S is a no barrier reaction channel. Reaction channel of S atom attacking Li2 molecule has a transition state. Channel of Li atom attacking LiS molecule has a transition state.
作者
许永强
彭伟成
蔡雨晴
XU Yongqiang PENG Weicheng CAI Yuqing(College of Physics and Electronic Information, Gannan Normal University, Ganzhou 341000, China School of Science, Xihua University, Chengdu 610039, China)
出处
《计算物理》
CSCD
北大核心
2016年第6期749-756,共8页
Chinese Journal of Computational Physics
基金
赣南师范学院自然科学研究课题(430374)资助项目
关键词
LI2
S
结构
多体项展式理论
势能面
Li2 S
structure
many-body expansion theory
potential energy surface
