Department of Physics and Astronomy, University College London, Gower St., London WC1E 6BT, United Kingdom.
J Chem Phys. 2012 Jan 14;136(2):024324. doi: 10.1063/1.3675448.
R-matrix calculations on electron collisions with the purine bases found in DNA and RNA (i.e., adenine and guanine) are presented. Resonant anion states of these systems are identified by employing different approximation levels of ab initio theoretical methods, such as the static exchange, the static exchange plus polarization, and the close-coupling methods. The results are compared with other available calculations and experiments. All of these ab initio approximations, which we refer to as a scattering "model," give four shape resonances of (2)A'' (π) symmetry within the energy range of 10 eV for both molecules. For adenine, the most sophisticated method, the close-coupling model, gives two very narrow (2)A' (σ) symmetry Feshbach-type resonances at energies above 5 eV. Quantitative results for the total elastic and electronic excitation cross sections are also presented.
呈现了电子与 DNA 和 RNA 中发现的嘌呤碱基（即腺嘌呤和鸟嘌呤）碰撞的 R 矩阵计算。通过采用不同的从头算理论方法近似水平，例如静态交换、静态交换加极化和密耦方法，确定了这些体系的共振阴离子态。将结果与其他可用的计算和实验进行了比较。所有这些我们称为散射“模型”的从头算近似方法，在两个分子的 10 eV 能量范围内给出了（2）A''（π）对称性的四个形状共振。对于腺嘌呤，最复杂的方法，即密耦模型，在 5 eV 以上的能量给出了两个非常窄的（2）A'（σ）对称性的 Feshbach 型共振。还给出了总弹性和电子激发截面的定量结果。
