用密度泛函方法研究了ＬａＣ３ｎ（ｎ＝－１，０，＋１）分子簇的结构和稳定性，对这个四原子体系，提出了５种可能构型，其中３种具有Ｃ２ｖ对称性，２种为Ｃ∞ｖ对称性．在Ｃ２ｖ对称性结构中，其中１个为Ｌａ接在弯曲的Ｃ３链上，第２个是Ｌａ通过２个键与Ｃ３环相链，第３个是Ｌａ通过１个键与Ｃ３环相连；在Ｃ∞ｖ对称性中，第１个Ｌａ接在Ｃ３链的一端，而在第２个构型中，Ｌａ被插入在Ｃ３链中．结果表明，环状结构当Ｌａ接在弯曲的Ｃ３链上的是局域极小值并且最稳定 The structure and stability of LaC3n (n = -1, 0, + 1) clusters have been studied by means of density functional theory. Five possible configurations for this four-atom system have been proposed. Three of them have C2v symmetry and two C ∞ v symmetry. In C2v symmetry structure, one is La is connected to the curved C3 chain, the second is La linked to C3 ring by two bonds, the third is La linked to C3 by one bond; In C∞v symmetry, the first La is attached to one end of the C3 chain, while in the second configuration La is inserted into the C3 chain. The results show that the ring structure is the local minimum and the most stable when La is attached to the curved C3 chain