Solute-Solvent Charge-Transfer Excitations and Optical Absorption of Hydrated Hydroxide from Time-Dependent Density-Functional Theory.
Solute-Solvent Charge-Transfer Excitations and Optical Absorption of Hydrated Hydroxide from Time-Dependent Density-Functional Theory.
复制标题
根据时变密度泛函理论研究水合氢氧化物的溶质-溶剂电荷转移激发和光学吸收
DOI：
10.1021/ct5002889
复制
发表时间：
2014
影响因子：
5.5
通讯作者：
M. Sprik
中科院分区：
文献类型：
--
作者：
D. Opalka;M. Sprik
简单水合离子的电子结构是电子结构理论中最具挑战性的问题之一。光谱实验确定的最低激发态的溶剂化氢氧化物作为电荷转移到溶剂（CTTS）状态。在目前的工作中，我们报告的溶剂化氢氧离子的吸收光谱的计算，处理溶剂和溶质严格在同一理论水平。平均吸收光谱高达25 eV已计算周期性从头计算分子动力学模拟的样品。在广义梯度近似（GGA）和混合密度泛函下分析了实验观察到的吸收阈值附近的CTTS态。根据HSE混合泛函和Davidson对角化方案计算的最低激发能的结果，CTTS跃迁已被发现低于液态水的第一吸收带0.6 eV。电子向溶剂的转移可以归因于从溶质2pπ轨道到溶剂的显著离域的最低未占轨道的激发，溶质2pπ轨道由于不对称溶剂环境而受到小的能量分裂。激发态中心的分布表明，CTTS沿着OH轴的氢氧根离子是避免的。此外，我们的模拟表明，在GGA计算的光谱中产生的系统误差源于溶液中的价带能量的描述不佳。
The electronic structure of simple hydrated ions represents one of the most challenging problems in electronic-structure theory. Spectroscopic experiments identified the lowest excited state of the solvated hydroxide as a charge-transfer-to-solvent (CTTS) state. In the present work we report computations of the absorption spectrum of the solvated hydroxide ion, treating both solvent and solute strictly at the same level of theory. The average absorption spectrum up to 25 eV has been computed for samples taken from periodic ab initio molecular dynamics simulations. The experimentally observed CTTS state near the onset of the absorption threshold has been analyzed at the generalized-gradient approximation (GGA) and with a hybrid density-functional. Based on results for the lowest excitation energies computed with the HSE hybrid functional and a Davidson diagonalization scheme, the CTTS transition has been found 0.6 eV below the first absorption band of liquid water. The transfer of an electron to the solvent can be assigned to an excitation from the solute 2pπ orbitals, which are subject to a small energetic splitting due to the asymmetric solvent environment, to the significantly delocalized lowest unoccupied orbital of the solvent. The distribution of the centers of the excited state shows that CTTS along the OH–axis of the hydroxide ion is avoided. Furthermore, our simulations indicate that the systematic error arising in the calculated spectrum at the GGA originates from a poor description of the valence band energies in the solution.
登录
查看更多内容
影响因子：
4.4
作者：
Costanzo, Francesca;Sulpizi, Marialore;Sprik, Michiel
通讯作者：
Sprik, Michiel
影响因子：
15
作者：
Adriaanse, Christopher;Sulpizi, Marialore;Sprik, Michiel
通讯作者：
Sprik, Michiel
影响因子：
8.6
作者：
J. Perdew;K. Burke;M. Ernzerhof
通讯作者：
J. Perdew;K. Burke;M. Ernzerhof
影响因子：
5.7
作者：
Adriaanse, Christopher;Cheng, Jun;Sprik, Michiel
通讯作者：
Sprik, Michiel
影响因子：
4.4
作者：
Rubio, Mercedes;Serrano-Andres, Luis;Merchan, Manuela
通讯作者：
Merchan, Manuela