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首页> 外文期刊>Physical chemistry chemical physics: PCCP >Photoreaction channels of the guanine-cytosine base pair explored by long-range corrected TDDFT calculations
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Photoreaction channels of the guanine-cytosine base pair explored by long-range corrected TDDFT calculations

机译：鸟嘌呤-胞嘧啶碱基对的光反应通道通过远程校正的TDDFT计算探索

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摘要

Photoinduced processes in the Watson-Crick guanine-cytosine base pair are comprehensively studied by means of long-range corrected (LC) TDDFT calculations of potential energy profiles using the LC-BLYP and CAM-B3LYP functionals. The ab initio CC2 method and the conventional TDDFT method with the B3LYP functional are also employed to assess the reliability of the LC-TDDFT method. The present approach allows us to compare the potential energy profiles at the same computational level for excited-state reactions of the base pair, including single and double proton transfer between the bases and nonradiative decay via ring puckering in each base. In particular, long-range correction to the TDDFT method is critical for a qualitatively correct description of the proton transfer reactions. The calculated energy profiles exhibit low barriers for out-of-plane deformation of the guanine moiety in the locally-excited state, which is expected to lead to a conical intersection with the ground state, as well as for single proton transfer from guanine to cytosine with the well-known electron-driven proton transfer mechanism. Thus the present results suggest that both processes can compete in hydrogen-bonded base pairs and play a significant role in the mechanism of photostability.
机译：沃森-克里克鸟嘌呤-胞嘧啶碱基对中的光诱导过程已通过使用LC-BLYP和CAM-B3LYP功能进行的长势校正（LC）TDDFT计算势能图进行了全面研究。从头开始使用CC2方法和具有B3LYP功能的常规TDDFT方法也可用来评估LC-TDDFT方法的可靠性。本方法使我们能够比较相同计算水平下碱基对的激发态反应的势能分布，包括碱基之间的单质子传递和双重质子传递以及每个碱基中通过环褶皱产生的非辐射衰变。特别地，对于质子转移反应的定性正确描述，TDDFT方法的远程校正至关重要。计算出的能量分布对在局部激发态的鸟嘌呤部分的面外变形表现出较低的势垒，这有望导致与基态的圆锥形相交，以及从鸟嘌呤向胞嘧啶的单质子转移具有众所周知的电子驱动质子转移机制。因此，目前的结果表明这两个过程都可以竞争氢键碱基对，并在光稳定性机制中起重要作用。

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