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首页> 外文期刊>The Journal of Chemical Physics >Proton and deuteron position preferences in water clusters: An ab initio study
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Proton and deuteron position preferences in water clusters: An ab initio study

机译：水簇中质子和氘核的位置偏好：从头算研究

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In order to explore the effect of H-to-D substitution on the zero-point energy (ZPE) of water clusters,Hessians were computed for a database of 53 optimized (H_2O)_n clusters,5 <= n <= 21,at the B3LYP/6-311 + +G~(**) level.The 53 clusters contained 1524 protons,which were sorted into 18 categories according to the type of their donor O and (if not free) acceptor O.Letting DELTAZPE{H~*} denote the change in ZPE when the proton H~* is replaced by D,mean values for DELTAZPE{H~*} for the H-bonded categories ranged from -2172 cal mol~(-1) for H~* in a DDAA-DDAA bond to -2118 for H~* in a DAA-DDA bond.Mean value for H* free on DAA (respectively,DA) was -2018 (respectively,-1969).For DAA-DDA bonds,and for short H bonds in general,there was a strong inverse correlation between |DELTAZPE{H~*}| and the O-H~* distance.DELTA ZPE for multiple H-to-D substitutions was additive,except for a cooperativity effect of -13.7 to -19.7 cal mol~(-1) when two substituted protons were in the same H_2O unit and a much smaller cooperativity when one proton's donor was the other's acceptor.Implications of these data include a relative preference for D to occupy H bonded rather than free positions in finite water clusters,a value of 3.82 for the disproportionation equilibrium constant of mixed ice at 150 K,increased occupation by H at surface positions of mixed ice,and a larger average coordination number for liquid D_2O than for liquid H_2O.
机译：为了探索H-to-D替代对水团簇的零点能量（ZPE）的影响，针对53个优化的（H_2O）_n团簇，5 <= n <= 21 B3LYP / 6-311 + + G〜（**）的水平。这53个簇包含1524个质子，根据其供体O和（如果不是自由的话）受体O的类型分为18类。 〜*}表示将质子H〜*替换为D时ZPE的变化，H键类型的DELTAZPE {H〜*}的均值范围为-2172 cal mol〜（-1）在DAA-DDA债券中，H〜*的DDAA-DDAA债券为-2118.DAA上游离H *的平均价值（分别为DA）为-2018（分别为-1969）.DAA-DDA债券以及通常，氢键短，| DELTAZPE {H〜*} |之间有很强的反相关性。多个H到D取代的DELTA ZPE是可加的，除了当两个被取代的质子在相同的H_2O单元和一个H_2O单元中时-13.7至-19.7 cal mol〜（-1）的协同作用。当一个质子的供体是另一个质子的供体时，合作性要小得多。这些数据的含义包括相对优先选择D来占据有限水簇中的H键合位置而不是自由位置，混合冰在150 K时的歧化平衡常数值为3.82。 ，增加了冰在混合冰表面位置的占有，并且液体D_2O的平均配位数大于液体H_2O。

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