Ionization and Electron Attachment for Nucleobases in Water
Ionization and Electron Attachment for Nucleobases in Water
复制标题
水中核碱基的电离和电子附着
DOI：
10.1021/acs.jpcb.8b09435
复制
发表时间：
2019
影响因子：
3.3
通讯作者：
Han Keli
中科院分区：
文献类型：
--
作者：
Zhang Yan;Xie Peng;Yang Songqiu;Han Keli
我们使用量子力学/力学分子（QM/MM）联合方法研究了水中核碱基的电离和电子附着。我们首先探讨了快照数量和qm区域大小，以得到收敛的结果。20个快照的计算可以得到收敛的物理量，收敛的QM区域包含大约100个原子。计算了五种碱在显式水溶液中的垂直电离能、绝热电离能、垂直电子亲和能、绝热电子亲和能和垂直脱离能。胞嘧啶和胸腺嘧啶在水溶液中的计算值与实验值吻合较好。这五个物理量的结果表明，体积水的qm区极化对电离和电子附着有明显的影响。在电离和电子附着过程中，空穴或多余的电子并不完全定位在核碱基上。QM区的极化和QM原子的运动导致结构弛豫中正离子和阴离子能量的急剧下降（正离子为~ 2.1 eV，阴离子为~ 2.9 eV）。在平衡结构附近，正离子和阴离子的势能面会变得非常陡。
We used a combined quantum mechanical/mechanical molecular (QM/MM) method to investigate ionization and electron attachment for nucleobases in water. We first explored the snapshot number and QM-region size to get converged results. The computations of 20 snapshots can get converged physical quantities and converged QM regions contain about 100 atoms. We computed the vertical ionization energies (VIEs), adiabatic ionization energies, vertical electron affinities, adiabatic electron affinities, and vertical detachment energies of five bases in the explicit aqueous solvent. The computational VIEs of cytosine and thymine agree well with the experimental values in aqueous solutions. The results of the five physical quantities indicate that the QM-region polarization by bulk water evidently affects the ionization and electron attachment. Holes or excess electrons do not entirely localize on nucleobases in the ionization and electron attachment. The QM-region polarization and the movements of the QM atoms induce a drastic decrease (∼2.1 eV for cation and ∼2.9 eV for anion) of the cationic and anionic energies in structural relaxations. The potential energy surfaces of the cation and anion would become very steep near the equilibrium structure.