Interpretation of vibrational IR spectrum of uracil using anharmonic calculation of frequencies and intensities in second-order perturbation theory |
| |
Authors: | G N Ten V V Nechaev and S V Krasnoshchekov |
| |
Institution: | (1) School of Materials and Chemical Engineering, Zhongyuan University of Technology, Zhongyuan Road 41#, Zhengzhou, 450007, China |
| |
Abstract: | The anharmonic frequencies of fundamental vibrations, overtones, and combination vibrations, as well as the intensities of
absorption bands in the IR spectrum of uracil, are calculated. The anharmonic quartic force field and the third-order dipole
moment surface calculated by the DFT quantum-mechanical method (B3LYP/6-31+G(d,p)) are taken as the initial parameters. The anharmonic frequencies and intensities of vibrations are determined using the
second-order perturbation theory in the form of contact transformations. Multiple Fermi resonances and polyads are determined
by the diagonalization of a small interaction matrix of vibrations of different types (fundamental, combination, and overtone
frequencies). The total experimental IR spectrum of matrix-isolated uracil is interpreted. It is shown that the used method
of calculating anharmonic frequencies and intensities can form a basis for anharmonic calculations of vibrations of moderate
molecules. |
| |
Keywords: | |
本文献已被 SpringerLink 等数据库收录! |
|