Alam Mohammad Jane, Ahmad Shabbir
Department of Physics, Aligarh Muslim University, Aligarh 202002, India.
Department of Physics, Aligarh Muslim University, Aligarh 202002, India.
Spectrochim Acta A Mol Biomol Spectrosc. 2014 Jul 15;128:653-64. doi: 10.1016/j.saa.2014.02.170. Epub 2014 Mar 12.
FTIR, FT-Raman and UV-Vis spectra of 3-methyladenine have been recorded and investigated using quantum chemical calculations. The molecular geometry and vibrational spectra of 3-methyladenine in the ground state are computed by using HF and DFT methods with 6-311G(d,p) basis set. VSCF, CC-VSCF methods based on 2MR-QFF and PT2 (Barone method) have been utilized for computing anharmonic vibrational frequencies. These methods yield results that are in remarkable agreement with the experimental data. The magnitudes of coupling between pair of modes have been also computed. Vibrational modes are assigned with the help of visual inspection of atomic displacements. The electronic spectra, simulated at TD-B3LYP/6-311++G(d,p) level of theory, are compared to the experiment. The global quantities: electronic chemical potential, electrophilicity index, chemical hardness and softness based on HOMO and LUMO energy eigenvalues are also computed at B3LYP/6-311++G(d,p) level of theory.
已记录了3-甲基腺嘌呤的傅里叶变换红外光谱（FTIR）、傅里叶变换拉曼光谱（FT-Raman）和紫外可见光谱（UV-Vis），并使用量子化学计算进行了研究。通过使用HF和DFT方法以及6-311G(d,p)基组，计算了基态下3-甲基腺嘌呤的分子几何结构和振动光谱。基于2MR-QFF的VSCF、CC-VSCF方法以及PT2（巴罗内方法）已用于计算非谐振动频率。这些方法得出的结果与实验数据非常吻合。还计算了模式对之间的耦合强度。借助对原子位移的目视检查来指定振动模式。在TD-B3LYP/6-311++G(d,p)理论水平下模拟的电子光谱与实验进行了比较。还在B3LYP/6-311++G(d,p)理论水平下计算了基于最高占据分子轨道（HOMO）和最低未占据分子轨道（LUMO）能量本征值的全局量：电子化学势、亲电性指数、化学硬度和软度。
