Split operator method for the nonadiabatic (J=0) bound states and (A <- X)absorption spectrum of NO2

A split operator three-dimensional wave packet propagation method is adapte d for the determination of the bound states and absorption band shape of NO 2 molecule presenting a conical intersection between its ground X (2)A(1) a nd first excited A B-2(2) electronic states. The numerical task, basically resting on a Fourier transform methodology, may present interesting advanta ges over matrix diagonalization techniques. The calculations of bound level s over a wide energy range and the absorption (A B-2(2)<--X(2)A(1)) band sh ape, extending up to 40000 cm(-1), are put on an equal footing by a nonadia batic three-dimensional wave packet propagation using available ab initio p otential energy surfaces. Good agreement is obtained when comparing the cal culated absorption spectrum to experimental data in a low resolution limit. The position and amplitude of the band shape are determined within only 2 and 3% of relative error, respectively, the total width being still overest imated by about 15%. An analysis of the causes of errors is presented stres sing the need for more accurate transition dipole moment determinations. (C ) 2001 American Institute of Physics.