scholarly journals Diagonal Born–Oppenheimer corrections to the ground electronic state potential energy surfaces of ozone: improvement of ab initio vibrational band centers for the 16O3, 17O3 and 18O3 isotopologues

2020 ◽  
Vol 22 (42) ◽  
pp. 24257-24269 ◽  
Author(s):  
Attila Tajti ◽  
Péter G. Szalay ◽  
Roman Kochanov ◽  
Vladimir G. Tyuterev
Keyword(s):  
Potential Energy ◽  
Ab Initio ◽  
Electronic State ◽  
Potential Energy Surfaces ◽  
Vibrational Band ◽  
Ground Electronic State ◽  
Vibrational Levels ◽  
State Potential ◽  
Energy Surfaces

The accuracy of variationally calculated vibrational levels of ozone can be greatly improved by adding diagonal Born–Oppenheimer correction to the best available ab initio potential.

Potential Energy Surfaces

1996 ◽  
Author(s):  
Tomas Baer ◽  
William L. Hase
Keyword(s):  
Potential Energy ◽  
Potential Energy Surface ◽  
Electronic State ◽  
Diatomic Molecule ◽  
Potential Energy Surfaces ◽  
Energy Surface ◽  
Electronic States ◽  
Dissociation Energies ◽  
State Potential ◽  
Energy Surfaces

Properties of potential energy surfaces are integral to understanding the dynamics of unimolecular reactions. As discussed in chapter 2, the concept of a potential energy surface arises from the Born-Oppenheimer approximation, which separates electronic motion from vibrational/rotational motion. Potential energy surfaces are calculated by solving Eq. (2.3) in chapter 2 at fixed values for the nuclear coordinates R. Solving this equation gives electronic energies Eie(R) at the configuration R for the different electronic states of the molecule. Combining Eie(R) with the nuclear repulsive potential energy VNN(R) gives the potential energy surface Vi(R) for electronic state i (Hirst, 1985). Each state is identified by its spin angular momentum and orbital symmetry. Since the electronic density between nuclei is different for each electronic state, each state has its own equilibrium geometry, sets of vibrational frequencies, and bond dissociation energies. To illustrate this effect, vibrational frequencies for the ground singlet state (S0) and first excited singlet state (S1) of H2CO are compared in table 3.1. For a diatomic molecule, potential energy surfaces only depend on the internuclear separation, so that a potential energy curve results instead of a surface. Possible potential energy curves for a diatomic molecule are depicted in figure 3.1. Of particular interest in this figure are the different equilibrium bond lengths and dissociation energies for the different electronic states. The lowest potential curve is referred to as the ground electronic state potential. The primary focus of this chapter is the ground electronic state potential energy surface. In the last section potential energy surfaces are considered for excited electronic states. A unimolecular reactant molecule consisting of N atoms has a multidimensional potential energy surface which depends on 3N-6 independent coordinates. For the smallest nondiatomic reactant, a triatomic molecule, the potential energy surface is four-dimensional (three independent coordinates plus the energy). Since it is difficult, if not impossible, to visualize surfaces with more than three dimensions, methods are used to reduce the dimensionality of the problem in portraying surfaces. In a graphical representation of a surface the potential energy is depicted as a function of two coordinates with constraints placed on the remaining 3N-8 coordinates.

scholarly journals Diagonal Born-Oppenheimer Corrections to the Ground Electronic State Potential Energy Surfaces of Ozone: Improvement of Ab Initio Vibrational Band Centers for the 16O3, 17O3 and 18O3 Isotopologues

2020 ◽  
Author(s):  
Attila Tajti ◽  
Péter Szalay ◽  
Roman V. Kochanov ◽  
Vladimir G. Tyuterev
Keyword(s):  
Potential Energy ◽  
Ab Initio ◽  
Potential Energy Surfaces ◽  
Vibrational States ◽  
Theoretical Predictions ◽  
Order Of Magnitude ◽  
State Potential ◽  
Effective Models ◽  
Energy Surfaces ◽  
Mass Dependent

<div>Mass-dependent diagonal Born-Oppenheimer corrections (DBOC) to the ab initio electronic ground state potential energy surface for tseveral isotopologues of the ozone molecule are reported for the first time. The comparison with experimental band centers shows a significant improvement of the accuracy with respect to the best Born-Oppenheimer (BO) ab initio calculations reducing the total root-mean-squares (calculated - observed) deviations by about factor of two. For the set of 16O3 vibrations up to five bending and four stretching quanta, the mean (calculated - observed) deviations drop down from 0.7 cm-1 (BO) to about 0.1 cm-1, with the most pronounced improvement seen for bending states and for mixed bend-stretch polyads. In case of bending band centers directly observed under high spectral resolutions, the errors are reduced by more than order of magnitude from observed levels, approaching nearly experimental accuracy. New sets of ab initio vibrational states can be used for improving spectroscopic effective models for analyses of observed high-resolution spectra, particularly in cases of accidental resonances with ,,dark'' states requiring accurate theoretical predictions.</div>

scholarly journals Quantum dynamical study of the O(D1)+HCl reaction employing three electronic state potential energy surfaces

2008 ◽  
Vol 128 (1) ◽  
pp. 014308 ◽  
Author(s):  
Huan Yang ◽  
Ke-Li Han ◽  
Shinkoh Nanbu ◽  
Hiroki Nakamura ◽  
Gabriel G. Balint-Kurti ◽  
...  
Keyword(s):  
Potential Energy ◽  
Electronic State ◽  
Potential Energy Surfaces ◽  
Dynamical Study ◽  
Quantum Dynamical ◽  
State Potential ◽  
Energy Surfaces
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