scholarly journals Orbital Energies and Nuclear Forces in DFT: Interpretation and Validation

2020 ◽  
Author(s):  
Rubén Laplaza ◽  
Julia Contreras-Garcia ◽  
Patrick Chaquin ◽  
Carlos Cardenas ◽  
Paul W. Ayers
Keyword(s):  
Excited State ◽  
Ab Initio Calculations ◽  
Ab Initio ◽  
Molecular Orbitals ◽  
Conceptual Dft ◽  
Orbital Energy ◽  
Nuclear Forces ◽  
Energy Derivatives ◽  
Koopmans Theorem ◽  
General Derivation

The bonding and antibonding character of individual Molecular Orbitals has been previously shown to be related to their orbital energy derivatives with respect to nuclear coordinates, known as Dynamical Orbital Forces. Albeit usually derived from Koopmans' theorem, in this work we show a more general derivation from conceptual DFT, which justifies application in a broader context. The consistency of the approach is validated numerically for valence orbitals in Kohn-Sham DFT. Then, we illustrate its usefulness by showcasing applications in aromatic and antiaromatic systems and in excited state chemistry. Overall, Dynamical Orbital Forces can be used to interpret the results of routine ab initio calculations, be it wavefunction or density based, in terms of forces and occupations.

scholarly journals Orbital Energies and Nuclear Forces in DFT: Interpretation and Validation

2020 ◽  
Author(s):  
Rubén Laplaza ◽  
Julia Contreras-Garcia ◽  
Patrick Chaquin ◽  
Carlos Cardenas ◽  
Paul W. Ayers
Keyword(s):  
Excited State ◽  
Ab Initio Calculations ◽  
Ab Initio ◽  
Molecular Orbitals ◽  
Conceptual Dft ◽  
Orbital Energy ◽  
Nuclear Forces ◽  
Energy Derivatives ◽  
Koopmans Theorem ◽  
General Derivation

The bonding and antibonding character of individual Molecular Orbitals has been previously shown to be related to their orbital energy derivatives with respect to nuclear coordinates, known as Dynamical Orbital Forces. Albeit usually derived from Koopmans' theorem, in this work we show a more general derivation from conceptual DFT, which justifies application in a broader context. The consistency of the approach is validated numerically for valence orbitals in Kohn-Sham DFT. Then, we illustrate its usefulness by showcasing applications in aromatic and antiaromatic systems and in excited state chemistry. Overall, Dynamical Orbital Forces can be used to interpret the results of routine ab initio calculations, be it wavefunction or density based, in terms of forces and occupations.

A comprehensive study of cold protonated tyramine: UV photodissociation experiments and ab initio calculations

2015 ◽  
Vol 17 (39) ◽  
pp. 25854-25862 ◽  
Author(s):  
Michel Broquier ◽  
Satchin Soorkia ◽  
Gilles Grégoire
Keyword(s):  
Excited State ◽  
Ab Initio Calculations ◽  
Ab Initio ◽  
Laser Spectroscopy ◽  
Comprehensive Study

Excited state properties of cold protonated ions are revealed by a combination of laser spectroscopy and ab initio calculations.

Ammonia oxide. I. Geometry and stability

1976 ◽  
Vol 29 (2) ◽  
pp. 231 ◽  
Author(s):  
BT Hart
Keyword(s):  
Excited State ◽  
Ab Initio Calculations ◽  
Ab Initio ◽  
Bond Length ◽  
Ground State ◽  
Tautomeric Form ◽  
Potential Curve ◽  
Repulsive Potential ◽  
Means Of Production

Ab initio calculations, utilizing Gaussian lobe functions, are reported for the molecule ammonia oxide, NH3O. Results indicate that ammonia oxide has a bound ground state, an abnormally long NO bond length (169 pm) and is 125.9 kJ mol-1 less stable than the tautomeric form hydroxylamine, NH2OH. Possible means of production of the molecule are discussed. The 3E excited state of ammonia oxide was found to have a repulsive potential curve. Possible reasons for this instability are advanced.

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