小分子钾团簇结构和性质的从头算研究
Ab initio studies of structures and properties of small potassium clusters
摘要：
我们在从头算水平上研究了含2 ~ 20个偶数原子的钾原子团簇的结构和性质。采用全电子密度泛函理论和梯度修正的交换相关泛函进行了几何优化计算。使用这些优化的几何形状，我们调查的结合能，电离势，和静态极化率随团簇的大小的演变。利用Moller-Plesset微扰理论和含时密度泛函理论计算了体系的极化率。采用大基组耦合团簇理论计算了二聚体和四聚体的极化率。用含时密度泛函理论计算了两种不同的交换关联势：（i）渐近正确的模型势和（ii）局域密度近似下的极化率。对上述小钾团簇的各种性质与其它已有的理论和实验数据进行了系统的比较。这些比较表明，无论是结合能和电离势梯度校正的潜力与已公布的数据匹配得很好。同样，用Moller-Plesset微扰理论和模型势得到的极化率也非常接近，与实验数据也很接近。
英文摘要：
We have studied the structure and properties of potassium clusters containing even number of atoms ranging from 2 to 20 at the ab initio level. The geometry optimization calculations are performed using all-electron density functional theory with gradient corrected exchange-correlation functional. Using these optimized geometries we investigate the evolution of binding energy, ionization potential, and static polarizability with the increasing size of the clusters. The polarizabilities are calculated by employing Moller-Plesset perturbation theory and time dependent density functional theory. The polarizabilities of dimer and tetramer are also calculated by employing large basis set coupled cluster theory with single and double excitations and perturbative triple excitations. The time dependent density functional theory calculations of polarizabilities are carried out with two different exchange-correlation potentials: (i) an asymptotically correct model potential and (ii) within the local density approximation. A systematic comparison with the other available theoretical and experimental data for various properties of small potassium clusters mentioned above has been performed. These comparisons reveal that both the binding energy and the ionization potential obtained with gradient corrected potential match quite well with the already published data. Similarly, the polarizabilities obtained with Moller-Plesset perturbation theory and with model potential are quite close to each other and also close to experimental data.
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