Normal modes for probing the local solvation environment of nitrate anion during step wise hydration: A theoretical study

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• 作者：Arup Kumar Pathak ; ^{akpathak@barc.gov.in}
• 关键词：Ab initio ; MP2 ; Normal mode ; Raman spectra ; Energy partitioning ; Cluster
• 刊名：Chemical Physics
• 出版年：2012
• 期刊代码：18_03010104
• 类别：ch
• 出版时间：25 May, 2012
• 卷：400
• 期：Complete
• 页码：86-92
• 文件大小：550 K

摘要

We investigate structural, energetic and spectroscopic aspects of the finite size hydrated  路 nH₂O (n = 1-8) clusters based on the first principles electronic structure calculations. It is observed that the geometrical parameters at MP2/6-311++G(d,p) level are almost equal to that of calculated at B3LYP/6-311++G(d,p) level for the higher size of clusters (n > 3). Our results reveal that total interaction energy and its components do vary linearly with the size of the clusters. Two types of scaling factors are implemented in two different regions to account the effect of anharmonic vibrations. The degeneracy of in-plane bending and asymmetric NO stretching mode in nitrate system is lifted due to hydration. An excellent agreement is observed between the present calculated H₂O bending and asymmetric NO stretching frequencies with the experimental results (within 4%w.r.t. experimentally measured values). Understanding the nature of normal modes of vibration at the molecular level provides information of the local hydration environment during stepwise solvation.