Accurate quantum dynamics simulation of the photodetachment spectrum of the nitrate anion (NO3−) based on an artificial neural network diabatic potential model

Abstract

The photodetachment spectrum of the nitrate anion (NO −3 ) is simulated from first principles using wavepacket quantum dynamics propagation and a newly developed accurate full-dimensional fully coupled five state diabatic potential model. This model utilizes the recently proposed complete nuclear permutation inversion invariant artificial neural network diabatization technique [D. M. G. Williams and W. Eisfeld, J. Phys. Chem. A 124, 7608 (2020)]. The quantum dynamics simulations are designed such that temperature effects and the impact of near threshold detachment are taken into account. Thus, the two available experiments at high temperature and at cryogenic temperature using the slow electron velocity-map imaging technique can be reproduced in very good agreement. These results clearly show the relevance of hot bands and vibronic coupling between the X 2 A ′ 2 ground state and the B 2 E ′ excited state of the neutral radical. This together with the recent experiment at low temperature gives further support for the proper assignment of the ν 3 fundamental, which has been debated for many years. An assignment of a not yet discussed hot band line is also proposed.

Simulation of the photodetachment spectra of the nitrate anion (NO3−) in the B̃ 2E′ energy range and non-adiabatic electronic population dynamics of NO3

“…These parameters are similar to the ones employed in ref. 13 when the comparison with the experimental data was done.…”

“…All wave packet propagations of the neutral NO 3 were carried out using our most recent full-dimensional diabatic PES model for the five involved electronic state components belonging to the X ˜, A ˜, and B ˜states. 13 This model utilizes a simple fitted loworder vibronic coupling Hamiltonian as reference model, which ensures to incorporate the correct physics at least qualitatively. This reference model then is tuned by an artificial neural network (ANN) to obtain the highest possible accuracy.…”

“…1. As in our previous work, 13 the full photodetachment spectrum is computed by two partial spectra obtained from putting the initial wave packet on either of the two electronic manifolds. The full spectrum (black line) is dominated by the contribution from the photodetachment into the B ˜state (red trace).…”

“…The theoretical treatment was driven by the development of more and more accurate models for the coupled potential energy surfaces (PESs). [1][2][3][4][5][6][7][8][9][10][11][12][13] This development was hampered initially by the artificial symmetry-breaking of the electronic wave function, which was discovered and solved in 2000. 14,15 Other key steps for the improvement of accuracy were the development of higher-order expansions of the diabatic JT Hamiltonian 5,10,16,17 and most recently the use of artificial neural networks (ANNs).…”

“…14,15 Other key steps for the improvement of accuracy were the development of higher-order expansions of the diabatic JT Hamiltonian 5,10,16,17 and most recently the use of artificial neural networks (ANNs). 13,[18][19][20][21] The ground state of NO 3 corresponds to a 2 A 0 2 state (X ˜) with a D 3h symmetric equilibrium geometry and the first two excited states transform as 2 E 00 (A ˜) and 2 E 0 (B ˜), respectively. The B ˜state is easily accessible in direct absorption and thus is known since the 1930s.…”