Theoretical study of valence orbital response to guanine tautomerization in coordinate and momentum spaces
Theoretical study of valence orbital response to guanine tautomerization in coordinate and momentum spaces
复制标题
DOI：
10.1088/0953-4075/48/20/205101
复制
发表时间：
2015-09
期刊：
影响因子：
--
通讯作者：
ZeJin Yang;P. Duffy;Quansong Zhu;M. Takahashi;Feng Wang
中科院分区：
文献类型：
--
作者：
ZeJin Yang;P. Duffy;Quansong Zhu;M. Takahashi;Feng Wang
计算了八种稳定鸟嘌呤互变异构体在完整价态空间中的结合能谱和电子动量谱。目前的结果表明，经典的酮（C=O）鸟嘌呤N（9）H互变异构体（GU1）具有最大的偶极矩、分子电子空间范围、分子硬度值和最小的第一垂直电离势（VIP）。价轨道分布研究发现，一些轨道在互变异构过程中几乎保持不变，例如前沿最高占据分子轨道39a和18a。还检测到了几个在电荷空间方向上具有互换顺序和相反方向的轨道。外层价轨道（具有较小的 VIP）在动量空间中比内层价轨道（较大的 VIP）表现出更复杂的轨道形状，这主要是由于相对较强的轨道间相互作用和离域电子分布。质子在六角环内沿 C–O(H) 和 C–N(H) 轴旋转对轨道剖面的影响比质子在五角环和/或六角环内迁移的影响更小。观察了烯醇（GU3-GU5）和酮（GU1、GU2、GU6-GU8）互变异构体之间的轨道变化趋势，包括烯醇形式的特征轨道、总轨道强度的变化趋势以及最大轨道强度的变化顺序。在外价动量空间（26a外），pz电子组成的轨道呈现单峰，峰位从0.5 a.u到逐渐增加。内价轨道为 1.0 a.u.外价轨道，而由 px,y 电子组成的轨道在大约 0.5 和 1.5 a.u. 处形成双峰，只有三个 px,y 轨道呈现单峰 (33a,34a,36a)。总结了所有价轨道在完整价空间中的强度、峰位和轨道成分的总体变化趋势。
The binding energy spectra and electron momentum spectra of eight stable guanine tautomers are calculated in the complete valence space. The present results show that the canonical keto (C=O) guanine N(9)H tautomer (GU1) possesses the largest dipole moment, molecular electronic spatial extent, molecular hardness value, and the minimum first vertical ionization potential (VIP). Valence orbital profile investigations find that several orbitals remain almost unchanged during tautomerization, such as frontier highest occupied molecular orbital 39a and 18a. Several orbitals with interchanged order and inverse direction in charge spatial orientations are also detected. Outer valence orbitals (with smaller VIPs) show more complex orbital shapes in the momentum space than those of inner ones (larger VIPs) due mainly to the relatively strong inter-orbital interaction and delocalized electronic distributions. Proton rotation along C–O(H) and C–N(H) axes within hexagonal ring causes smaller influence to orbital profiles than those of proton migration within pentagonal and/or hexagonal rings. Orbital variation trends between enol (GU3–GU5) and keto (GU1, GU2, GU6–GU8) tautomers are observed, including the signature orbitals of enol form, the variation tendency of total orbital intensity, and the variation order of the maximum orbital intensity. In the outer valence momentum space (outside 26a), orbital composed by pz electrons show single peak with a gradual increasing peak site from 0.5 a.u. of inner valence orbital to 1.0 a.u. of outer valence orbital, whereas orbitals composed by px,y electrons form double peaks with respective sites at about 0.5 and 1.5 a.u., only three px,y-orbitals present single peaks (33a,34a,36a). The general variation trends in the complete valence space for all the valence orbitals on their intensities, peak sites, and orbital components are concluded.