密度泛函理论的不同方法研究小钨团簇的结构与稳定性

分别利用密度泛函理论的LSDA方法和B3LYP 方法在有效核势基组(LanL2DZ)水平上系统地研究了Wn(n=2-14)团簇的结构和稳定性.Wn(n=2-14)团簇全局能量最小的最稳定结构被确定.结果表明:在所讨论的尺寸范围内,LSDA方法比B3LYP 方法得到的平均结合能与一阶能量差分高;大部分Wn(n=2-14) 团簇在两种方法计算下具有相同的几何结构.两种方法计算结果均表明:除了W3自旋多重度为3重态外,其余尺寸团簇的自旋多重度均为单重态;n=7的最低能量结构为双戴帽五边环,而非正十面体,n=8-10为笼型结构,n=11-14为扁长型结构.综合平均结合能、一阶能量差分和二阶能量差分,两种计算方法均表明Wn(n=2-14)团簇具有相同的幻数序列(2,6,9 和 13).

Study of structures and stabilities of small tungsten clusters by using density functional theory with different methods

The structures and stabilities of Wn(n=2-14) clusters were systematic studied by using density functional theory (DFT) at LSDA/LanL2DZ level and B3LYP/LanL2DZ level.The most stable structures of Wn(n=2-14) clusters with global energy minimum were determined.Our results shown that the average binding energy and the first differences of total energy from LSDA/LanL2DZ level are higher than that from B3LYP/LanL2DZ level.For most of Wn (n=2-14) clusters,the same global energy minimum geometrical structures were detected by using these two different methods.Results get from the two methods both shown that the spin multiplicity of all ground states for Wn(n=2-14) clusters,but W3 (W3 is triplet),are singlet.The bicapped five side rings-like structure is the lowest-energy con-gurations for n=7,not the decahedron geometry,and cage-like structures for n=8-10,prolate-like structures for n=11-14.The average binding energy,the first and second differences of total energy versus the sizes were all discussed.The same magic numbers (n=2,6,9 and 13) of Wn(n=2-14) clusters were obtained for the two different methods.