DVR study of the (A)over-tilde B-2(2)<-(X)over-tilde (2)A(1) absorption spectrum of NO2

摘要

Using available potential energy surfaces, a theoretical calculation of the (A) over tilde(2)B(2) <-- (X) over tilde(2)A(1) absorption spectrum of NO2 is presented. Energy levels and nuclear wave functions are calculated, using a discrete variable representation (DVR) basis expansion to solve the nuclear Schrodinger equation. Various energy regions of the absorption spectrum are considered. In the low-energy region, below the onset of the (A) over tilde(2)B(2) excited state, accurate results are recovered in a one-electronic-state calculation. It is also shown that using a decoupled potential energy surface derived from Schryber potential, accurate results are also obtained in the two-coupled-state case. Calculations are also performed in the higher energy part of the spectrum up to 16,000 cm(-1). Analysis of the calculated wave functions makes the assignment of vibrational quantum numbers possible for both electronic components to the various excited levels. Comparison with experimental results are presented. Reasonable agreement is obtained for the transition frequencies. An overall reliable reproduction of experimental data, including the intensities through Franck-Condon calculation, requires, however, the transition moment function as additional information. General conclusions concerning the Limitation of the model are discussed. (C) 1998 John Wiley & Sons, Inc. [References: 28]