中文摘要：

采用B3LYP/DZP＋＋的方法研究了第一水化层作用和连续化处理的水溶剂作用对鸟嘌呤-胞嘧啶（GC）碱基对和腺嘌呤-胸腺嘧啶（AT）碱基对质子转移反应的影响. GC和AT碱基对在连续化水溶剂作用下，均发生单质子转移（SPT1）和分步的双质子转移（DPT），而在第一水化层5 个水分子的作用下（GC·5H2O，AT·5H2O）或同时考虑第一水化层作用和连续化水溶剂作用（GC·5H2O＋PCM，AT·5H2O＋PCM）时，GC和AT碱基对的质子转移均只得到单质子转移反应（SPT1）. 单质子转移过程中的活化能变化情况表明：第一水化层对GC和AT碱基对结构和质子转移影响较大，水环境对碱基对的作用主要发生在第一水化层.

英文摘要：

The effects of the first hydration shell and the bulk solvation effects on the proton-transfer processes of guanine-cytosine （GC） and adenine-thymine （AT） base pairs are studied based on density functional theory, using the B3LYP method and DZP＋＋ basis set. The proton-transfer mechanisms of the GC and AT base pairs in bulk solvation are first single-proton transfer （SPT1） and stepwise double-proton transfer （DPT）. When only the first hydration shell surrounded by five water molecules （GC· 5H2O, AT1 5H20）, or both the first hydration shell and bulk solvation effects through polarizable continuum model （PCM） （GC· 5H2O＋PCM, AT· 5H2O＋PCM） are considered, only the first single-proton-transfer mechanism （SPT1） is found. The proton-transfer activation energies of the GC and the AT base pairs show that the majority of the hydration effects come from the first hydration shell through hydrogen-bond interactions, therefore the first hydration shell greatly influences the base pair structures and proton-transfer mechanism.