Indian Institute of Technology Bombay, Powai, Mumbai 400076, India.
Institute of Chemistry, Martin Luther University Halle-Wittenberg, Von-Danckelmann-Platz 4, 06120 Halle (Saale), Germany.
J Chem Theory Comput. 2021 Jan 12;17(1):105-116. doi: 10.1021/acs.jctc.0c00655. Epub 2020 Dec 30.
We present an explicit solvation protocol for the calculation of electron affinity values of the solvated nucleobases. The protocol uses a quantum mechanics/molecular mechanics (QM/MM) approach based on the newly implemented domain-based pair natural orbital EOM-CCSD (equation-of-motion coupled-cluster single-double) method. The stability of the solvated nucleobase anion is sensitive to the local distribution of the water molecules around the nucleobase, and the calculated electron affinity values converge slowly with respect to the number of snapshots and the size of the water box. The use of nonpolarizable water molecules leads to an overestimation of the electron affinity and makes the result sensitive to the size of the QM region in the QM/MM calculation. The electron affinity values, although sensitive to the size of the basis set, lead to an almost constant blue shift of the electron affinity upon the increase in the basis set. The present protocol allows for a controllable description of the various parameters affecting the electron affinity value, and the calculated adiabatic electron affinity values are in excellent agreement with experimental results.
我们提出了一种用于计算溶剂化碱基电子亲和度值的显式溶剂化方案。该方案使用了一种基于新实现的基于域的对自然轨道 EOM-CCSD（运动方程耦合簇单双）方法的量子力学/分子力学 (QM/MM) 方法。溶剂化碱基阴离子的稳定性对碱基周围水分子的局部分布敏感，并且电子亲和度值的计算随着快照数量和水盒大小的增加而缓慢收敛。使用不可极化水分子会导致电子亲和度的高估，并使结果对 QM/MM 计算中 QM 区域的大小敏感。电子亲和度值虽然对基组大小敏感，但会导致随着基组的增加，电子亲和度几乎呈常数蓝移。本方案允许对影响电子亲和度值的各种参数进行可控描述，并且计算得到的绝热电子亲和度值与实验结果非常吻合。
