Institute for Theoretical Chemistry, University of Vienna, Waehrinegrstrasse 17, A 1090 Vienna, Austria.
Phys Chem Chem Phys. 2010 May 21;12(19):4959-67. doi: 10.1039/b924956g. Epub 2010 Mar 29.
Semi-classical simulations of the UV-photoabsorption cross sections of adenine, guanine, cytosine, thymine, and uracil in gas phase were performed at the resolution-of-identity coupled cluster to the second-order (RI-CC2) level. With the exception of cytosine, the spectra of the other four nucleobases show a two band pattern separated by a low intensity region. The spectrum of cytosine is shaped by a sequence of three bands of increasing intensity. The first band of guanine is composed by two pipi* transitions of similar intensities. The analysis of individual contributions to the spectra allows a detailed assignment of bands. It is shown that the semi-classical simulations are able to predict general features of the experimental spectra, including their absolute intensities.
在同伦耦合簇到二阶（RI-CC2）水平上对气相中的腺嘌呤、鸟嘌呤、胞嘧啶、胸腺嘧啶和尿嘧啶的紫外光吸收截面进行了半经典模拟。除胞嘧啶外，其他四种碱基的光谱显示出由一个低强度区域隔开的两个带图案。胞嘧啶的光谱由一系列强度不断增加的三个带组成。鸟嘌呤的第一个带由两个强度相似的 pi-pi*跃迁组成。对光谱的各个贡献的分析允许对带进行详细的分配。结果表明，半经典模拟能够预测实验光谱的一般特征，包括它们的绝对强度。
