Al3+, Ca2+, Mg2+, and Li+ in aqueous solution: calculated first-shell anharmonic OH vibrations at 300 K.
Al3+, Ca2+, Mg2+, and Li+ in aqueous solution: calculated first-shell anharmonic OH vibrations at 300 K.
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水溶液中的 Al3 、Ca2 、Mg2 和 Li：计算 300 K 时的第一壳层非简谐 OH 振动。
DOI：
10.1063/1.3460261
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发表时间：
2010
期刊：
影响因子：
--
通讯作者：
K. Hermansson
中科院分区：
文献类型：
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作者：
L. Pejov;D. Spångberg;K. Hermansson
基于经典分子动力学（MD）模拟和量子力学（QM）计算，计算了稀水溶液中Li（+），Ca（2+），Mg（2+）和Al（3+）离子周围第一壳层水分子的非简谐OH伸缩振动频率ν（OH）.对于Li（+）（aq）、Ca（2+）（aq）、Mg（2+）（aq）和Al（3+）（aq），我们计算出的相对于气相水频率的IR频移Δν（OH）约为-300、-350、-450和-750 cm（-1），而实验红外（IR）研究为-290、-290、-420和-830 cm（-1）。 因此，除了Li（+）和Ca（2+）之间的顺序之外，一致性相当好。考虑到Ca（2+）离子的极化场应大于Li（+）（aq）离子的极化场，我们的计算结果是合理的。OH的绝对频率也与实验符合得很好。我们使用的方法是一个连续的四步程序：QM（电子）的力场+MD模拟+QM（电子）的点电荷嵌入M（n+）（H（2）O）（y）（第二壳层）（H（2）O）（z）（第三壳层）团簇+QM（振动）产生的OH光谱。 本文提出的多体Ca（2+）-水力场是新的。红外强度加权的状态密度的频率分布进行了通过平方的偶极矩导数。
The anharmonic OH stretching vibrational frequencies, ν(OH), for the first-shell water molecules around the Li(+), Ca(2+), Mg(2+), and Al(3+) ions in dilute aqueous solutions have been calculated based on classical molecular dynamics (MD) simulations and quantum-mechanical (QM) calculations. For Li(+)(aq), Ca(2+)(aq), Mg(2+)(aq), and Al(3+)(aq), our calculated IR frequency shifts, Δν(OH), with respect to the gas-phase water frequency, are about -300, -350, -450, and -750 cm(-1), compared to -290, -290, -420, and -830 cm(-1) from experimental infrared (IR) studies. The agreement is thus quite good, except for the order between Li(+) and Ca(2+). Given that the polarizing field from the Ca(2+) ion ought to be larger than that from Li(+)(aq), our calculated result seems reasonable. Also the absolute OH frequencies agree well with experiment. The method we used is a sequential four-step procedure: QM(electronic) to make a force field+MD simulation+QM(electronic) for point-charge-embedded M(n+) (H(2)O)(y) (second shell) (H(2)O)(z) (third shell) clusters+QM(vibrational) to yield the OH spectrum. The many-body Ca(2+)-water force-field presented in this paper is new. IR intensity-weighting of the density-of-states frequency distributions was carried out by means of the squared dipole moment derivatives.