Department of Chemistry, Indian Institute of Technology Guwahati, Guwahati 781 039, India.
J Chem Phys. 2012 Aug 14;137(6):064310. doi: 10.1063/1.4740461.
Effect of electron correlation on single strand breaks (SSBs) induced by low energy electron (LEE) has been investigated in a fragment excised from a DNA, viz., 2'-deoxycytidine-3'-monophosphate [3'-dCMPH] molecule in gas phase at DFT-B3LYP/6-31+G(d) accuracy level and using local complex potential based time dependent wave packet (LCP-TDWP) approach. The results obtained, in conjunction with our earlier investigation, show the possibility of SSB at very low energy (0.15 eV) where the LEE transfers from π∗ to σ∗ resonance state which resembles a S(N)2 type mechanism. In addition, for the first time, an indication of quantum mechanical tunneling in strand breaking is seen from the highest anionic bound vibrational state (χ(5)), which may have a substantial role during DNA damage.
在气相中，利用密度泛函理论（DFT）的 B3LYP 泛函和 6-31+G(d)基组，在一个 DNA 片段中切除的 2'-脱氧胞嘧啶核苷酸-3'-单磷酸（3'-dCMPH）分子上，研究了低能电子（LEE）引起的单链断裂（SSB）的电子相关效应，采用基于局部复势的含时波包（LCP-TDWP）方法。与我们之前的研究结果相结合，这些结果表明在非常低的能量（0.15 eV）下可能发生 SSB，此时 LEE 从 π到 σ共振态转移，类似于 S（N）2 型机制。此外，首次从最高阴离子束缚振动态（χ(5)）中观察到了链断裂的量子力学隧道效应，这在 DNA 损伤过程中可能起着重要作用。
