中文摘要：

采用密度泛函理论B3LYP方法得到了M@t-Bu-calix[4]arene和（M@t-Bu-calix[4]arene）Li′（M=Li, Na, K）体系的几何结构.其中（M@t-Bu-calix[4]arene）Li′（M=Li, Na, K）三个体系各有5个稳定异构体,在前三个异构体中,碱金属与t-Bu-calix[4]arene分子间具有很强的相互作用能,说明了体系的稳定性.在部分（M@t-Bu-calix[4]arene）Li异构体中Li′原子以阴离子形式存在,整个体系表现出碱金属化物的特性.此外,使用CAM-B3LYP方法计算了t-Bu-calix[4]arene及碱金属掺杂后体系的非线性光学性质.结果表明, t-Bu-calix[4]arene内部掺杂一个碱金属原子M后,体系的一阶超极化率（β0）有较大提高,而在配体外部又掺杂一个Li原子后,体系具有更大的β0值.其中（M@t-Bu-calix[4]arene）Li′体系的MLi′-4异构体表现出最高的β0值（41827-114354 a.u.）,并且随着M原子序数的增加而逐渐增大.可见,碱金属掺杂是提高t-Bu-calix[4]arene非线性光学响应的一种有效策略.

英文摘要：

Using density functional theory with the B3LYP functional, the optimized geometrical structures of the M@t-Bu-calix[4]arene and （M@t-Bu-calix[4]arene）Li′（M=Li, Na, K） compounds were obtained. Five stable isomers were identified for each bi-alkali-metal-doped （M@t-Bu-calix[4]arene）Li′species. The first three low-lying isomers have considerable intramolecular interaction energies between alkali metal atoms and the t-Bu-calix[4]arene molecule, indicating their stabilities. According to natural bond orbital analyses, the outside Li′atom is negatively charged in some （M@t-Bu-calix[4]arene）Li′structures, indicating the alkalide characteristics of these isomers. In addition, the nonlinear optical （NLO） properties of isolated and alkali-metal-doped t-Bu-calix [4]arene molecules were calculated using the CAM-B3LYP method. The results indicate that the single-doped effect of alkali metal M greatly enhances the first hyperpolarizability （β0） of the t-Bu-calix[4]arene molecule. In particular, when another Li atom is doped outside the M@t-Bu-calix[4]arene species, the resulting （M@t-Bu-calix[4]arene）Li′compounds exhibit largerβ0 values. Obviously, the alkali-metal-doping effect plays a crucial role. The MLi′-4 conformation has the largestβ0 value （41827-114354 a.u.） among al the （M@t-Bu-calix[4]arene） Li′structural isomers, and it is found that theβ0 value of （M@t-Bu-calix[4]arene）Li′gradually increases with increasing atomic number of the alkali metal M. Therefore, alkali-metal doping is an effective approach to enhance the NLO response of the t-Bu-calix[4]arene molecule.