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首页> 外文期刊>The Journal of Chemical Physics >Ab initio study of hydrated potassium halides KX(H2O)_(1-6)(X=F,CI,Br,l)
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Ab initio study of hydrated potassium halides KX(H2O)_(1-6)(X=F,CI,Br,l)

机译：水合卤化钾KX（H2O）_（1-6）（X = F，CI，Br，l）的从头算研究

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摘要

The ionic dissociation of salts was examined with a theoretical study of KX(X=F,Cl,Br,I)hydrated by up to six water molecules KX(H2O)n(n=1-6).Calculations were done using the density functional theory and second order Moller-Plesset(MP2)perturbational theory.To provide more conclusive results,single point energy calculations using the coupled cluster theory with single,double,and perturbative triple excitations were performed on the MP2 optimized geometries.The dissociation feature of the salts was examined in terms of K-X bond lengths and K-X stretch frequencies.In general,the successive incorporation of water molecules to the cluster lengthens the K-X distance,and consequently the corresponding frequency decreases.Near 0 K,the KX salt ion pairs can be partly separated by more than five water molecules.The pentahydrated KX salt is partly dissociated,though these partly dissociated structures are almost isoenergetic to the undissociated ones for KF/KC1.For the hexahydrated complexes,KF is undissociated,KCl/KBr is partly dissociated,and KI is dissociated(though this dissociated structure is nearly isoenergetic to a partly dissociated one).On the other hand,at room temperature,the penta- and hexahydrated undissociated structures which have less hydrogen bonds are likely to be more stable than the partly dissociated ones because of the entropy effect.Therefore,the dissociation at room temperature could take place for higher clusters than the hexahydrated ones.
机译：通过对多达六个水分子KX（H2O）n（n = 1-6）水合的KX（X = F，Cl，Br，I）进行理论研究，检查了盐的离子解离度，并使用密度进行了计算为了提供更多结论性的结果，在MP2优化的几何结构上，使用具有单，双和微扰三重激发的耦合聚类理论，对单点能量进行了计算。通常，水分子在团簇中的连续引入延长了KX的距离，因此相应的频率降低。在0 K附近，KX盐离子对可以是部分被五个以上的水分子隔开。五水合的KX盐被部分解离，尽管对于KF / KC1，这些部分解离的结构几乎与未解离的结构等能量。对于六水合物，KF未解离，KCl / KBr部分解离，KI解离（尽管此解离结构几乎与部分解离的同能）。另一方面，在室温下，具有较少氢键的五水合和六水合未解离结构由于熵的作用，它们可能比部分离解的更稳定。因此，室温下的离解比六水合的簇更易发生。

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