La_2C分子的MP2及密度泛函理论研究

THEORETICAL INVESTIGATION OF La2C CLUSTER

利用ＭＰ２及密度泛函方法（ＢＨＬＹＰ，Ｂ３Ｐ８６，Ｂ３ＬＹＰ）研究了Ｌａ２Ｃ分子的结构与稳定性，对Ｌａ２Ｃ分子共提出了两种构型，其中一种具有Ｃ２ｖ对称性，另一种为线型结构具有Ｄ∞ｈ对称性。计算结果表明，尽管对ＭＰ２和ＢＨＬＹＰ方法，线型结构较稳定，而对Ｂ３Ｐ８６及Ｂ３ＬＹＰ，Ｃ２ｖ结构较稳定，两结构在能量上很接近，表明它们具有相近的稳定性。在Ｄ∞ｈ对称性中其离子性要大于相应的Ｃ２ｖ对称性结构。

a2C cluster has been studied using density functional method. Two isomers were presented for this cluster, which have C2v and D∞h symmetry respectively. Four different density functional methods were used, wmch are MP2, BHLYP, B3P86, and B3LYP respectively. The results show that at MP2 and BHLYP levels, linear isomer with D∞h symmetry is the ground state and the most stable, while at B3P86 and B3LYP levels, isomer with C2v symmetry is the most stable. The results also indicate that the two structures are near isoenergetic and hence competitive for the groung state. The ionicity in linear isomer is greater than its corresponding values in C2v isomer for all four methods.