Low-lying Adiabatic Electronic States of NO: a QMC Study

Abstract

Abstract. Using Diffusion Monte Carlo in the fixed node approximation (FN-DMC) we have computed the electronic energy curves for some low lying doublet and quartet adiabatic states of NO. By starting with compact trial wave functions, we obtained accurate results in a wide range of internuclear distances. We have also been able to compute some spectroscopic properties and to interpret UV and visible absorption and emission spectra of NO in the gas phase by computing the Franck-Condon factors in the BornOppenheimer approximation. The comparison with available theoretical and experimental data is good.(doi: 10.5562/cca2302)

A comprehensive study of the radiative properties of NO—a first step toward a complete air opacity

“…The X 2 Π ground state has been the most extensively studied state, whether as the focus of the study or studied as part of a band system. For example, the PEC of the X 2 Π state was calculated using MRCI [127,128,[130][131][132][133][134][135][136][137][138][139][140][141][142], CAS-AQCC [143], and fixed-node diffusion Monte Carlo [144]. For the low-lying electronic states, the a 4 Π state has been studied with MRCI [127,129,133,141], DFT and CCSD(T) [145], and fixed-node diffusion Monte Carlo [144], while the A 2 Σ + and D 2 Σ + states have been studied with DFT and CCSD(T) [145], and MRCI in references [128, 132-134, 138, 142] and [132,135], respectively.…”

“…For example, the PEC of the X 2 Π state was calculated using MRCI [127,128,[130][131][132][133][134][135][136][137][138][139][140][141][142], CAS-AQCC [143], and fixed-node diffusion Monte Carlo [144]. For the low-lying electronic states, the a 4 Π state has been studied with MRCI [127,129,133,141], DFT and CCSD(T) [145], and fixed-node diffusion Monte Carlo [144], while the A 2 Σ + and D 2 Σ + states have been studied with DFT and CCSD(T) [145], and MRCI in references [128, 132-134, 138, 142] and [132,135], respectively. The 2 2 Π adiabatic (or C 2 Π and B 2 Π diabatic) state(s) has been modeled with DFT and CCSD(T) [145] and MRCI [133,136,[138][139][140]142].…”

Variational quantum Monte Carlo results for N2, N2+ and C2– utilising the four-dimensional density of Bright Wilson

“…In this work, we use a Jastrow factor that contains electron-nuclear, electron-electron, and electron-electron-nuclear terms [12]. The determinantal part of the wave function, instead, has been constructed by means of a recipe successfully used by Giannelli and Amovilli for the study of low lying states of NO molecule [13]. Following this recipe, the selection of the determinants is done in two steps: a first selection is performed from an extended CASSCF involving all the valence electrons by considering all excited configurations up to a given order of excitation with respect to the main configuration and, in the second step, by introducing a threshold on the determinant coefficients which allows the recovering of at least 97 percent of the resulting configuration interaction (CI) probability distribution.…”

Estrutura eletrônica, espectroscopia e dinâmica quase-clássica de sistemas moleculares: um estudo teórico

“…( 2 [216] é possível verificar situação semelhante, com ∆ T e próximo de -2.503 cm −1 . Já para Giannelli e Amovilli [217] o estado dubleto B está localizado acima do estado quarteto b com ∆ T e = 1.186 cm −1 . Nosso resultado é de ∆ T e = 1.622 cm −1 , em linha com o resultado experimental e o de Giannelli e Amovilli.…”