scholarly journals Accuracy of Spin-Component Scaled ADC(2) Excitation Energies and Potential Energy Surfaces

2019 ◽  
Vol 16 (1) ◽  
pp. 468-474 ◽  
Author(s):  
Attila Tajti ◽  
Levente Tulipán ◽  
Péter G. Szalay
Keyword(s):  
Potential Energy ◽  
Potential Energy Surfaces ◽  
Spin Component ◽  
Excitation Energies ◽  
Energy Surfaces

scholarly journals Accuracy of Spin-Component Scaled ADC(2) Excitation Energies and Potential Energy Surfaces

2019 ◽  
Author(s):  
Attila Tajti ◽  
Levente Tulipan ◽  
Péter Szalay
Keyword(s):  
Potential Energy ◽  
Excited States ◽  
Canonical Form ◽  
Potential Energy Surfaces ◽  
Second Order ◽  
Spin Component ◽  
Excitation Energies ◽  
Order Algebraic ◽  
Energy Surfaces

In a recent paper of this Journal (Tajti and Szalay, JCTC 2019, 15, 5523) we have shown that failures of the CC2 method to describe Rydberg excited states, as well as potential energy surfaces of certain valence excited states can be cured by spin-component scaled (SCS) versions SCS-CC2 and SOS-CC2 by a large extent. In this paper, the related and popular Second Order Algebraic Diagrammatic Construction (ADC(2)) method and its SCS variants are inspected with the previously established methodology. The results reflect the similarity of the CC2 and ADC(2) models, showing identical problems in the case of the canonical form and the same improvement when spin-component-scaling is applied.

scholarly journals Accuracy of Spin-Component Scaled ADC(2) Excitation Energies and Potential Energy Surfaces

2019 ◽  
Author(s):  
Attila Tajti ◽  
Levente Tulipan ◽  
Péter Szalay
Keyword(s):  
Potential Energy ◽  
Excited States ◽  
Canonical Form ◽  
Potential Energy Surfaces ◽  
Second Order ◽  
Spin Component ◽  
Excitation Energies ◽  
Order Algebraic ◽  
Energy Surfaces

In a recent paper of this Journal (Tajti and Szalay, JCTC 2019, 15, 5523) we have shown that failures of the CC2 method to describe Rydberg excited states, as well as potential energy surfaces of certain valence excited states can be cured by spin-component scaled (SCS) versions SCS-CC2 and SOS-CC2 by a large extent. In this paper, the related and popular Second Order Algebraic Diagrammatic Construction (ADC(2)) method and its SCS variants are inspected with the previously established methodology. The results reflect the similarity of the CC2 and ADC(2) models, showing identical problems in the case of the canonical form and the same improvement when spin-component-scaling is applied.

A CNDO/2 Calculation on the Reaction of Ground State Oxygen Atoms with Olefins

1974 ◽  
Vol 52 (2) ◽  
pp. 287-290 ◽  
Author(s):  
Seiichiro Koda
Keyword(s):  
Potential Energy ◽  
Ground State ◽  
Potential Energy Surfaces ◽  
Reaction Rate ◽  
Reaction Intermediates ◽  
Excitation Energies ◽  
Reaction Rate Constants ◽  
Molecular Orbital Study ◽  
Energy Surfaces ◽  
Oxygen Atoms

A molecular orbital study within the framework of the CNDO/2 method has been made of the reactions of ground state oxygen atoms with olefins. Calculated excitation energies confirm the existence of a certain correlation between those and the logarithm of the reaction rate constants. The location of minima in the simplified potential energy surfaces computed appear to correspond to the reaction intermediates suggested previously.

Refined potential-energy surfaces for the 2A" and à 2A' electronic states of the HO2 molecule

2001 ◽  
Vol 79 (2-3) ◽  
pp. 641-652 ◽  
Author(s):  
P Jensen ◽  
R J Buenker ◽  
J -P Gu ◽  
G Osmann ◽  
P R Bunker
Keyword(s):  
Dipole Moment ◽  
Potential Energy ◽  
Electric Dipole ◽  
Potential Energy Surfaces ◽  
Electronic States ◽  
Spin Component ◽  
Spin Orbit Coupling ◽  
Spin Orbit ◽  
Vibronic State ◽  
Energy Surfaces

In a previous paper (G. Osmann et al. J. Mol. Spectrosc. 197, 262 (1999)) we calculated ab initio the potential-energy surfaces of the ground [Formula: see text]2A" and excited Ã2A' electronic states of the HO2 molecule; these two states correlate with a 2Π state at linearity and participate in a Renner effect interaction. In that paper, we also calculated the electric- and magnetic-dipole moment and transition-moment surfaces, and the spin-orbit coupling constant; we then simulated the à ® [Formula: see text] emission band system including both electric-dipole and magnetic-dipole transitions. We now calculate more points on the surfaces to cover a wider range of bending geometries, and then refine the surfaces by fitting to rovibronic term values for both electronic states simultaneously. In the fitting we include levels having J values up to 9/2 and term values up to about 8000 cm–1. In our calculation of the energy levels we allow for the Renner effect and spin-orbit coupling by using our variational computer program RENNER. A good fitting to the data is obtained and as a result we obtain an accurate representation of these two potential surfaces over an energy range of more than 1 eV. We tabulate the vibronic energies up to 1 eV for both HO2 and DO2. We can explain the origin of a perturbation observed in the F1 spin component levels of the Ã(0, 0, 0) vibronic state for J values around 51/2; this is caused by a spin-orbit interaction satisfying Δ N = ± 1 with the F2 spin component levels of the [Formula: see text](1,1,2) vibronic state. Using the new rovibronic energies and wave functions, with our ab initio electric dipole moment and transition moment surfaces, we calculate Stark coefficients and compare them with experiment for some ground vibronic state levels. PACS Nos.: 31.20D, 31.50, 33.10, 33.20E, 35.20D, 35.20J

scholarly journals Improved Description of Charge Transfer Potential Energy Surfaces via Spin-Component Scaled CC2 and ADC(2) Methods

2020 ◽  
Author(s):  
Attila Tajti ◽  
Balázs Kozma ◽  
Péter Szalay
Keyword(s):  
Charge Transfer ◽  
Potential Energy ◽  
Potential Energy Surfaces ◽  
Spin Component ◽  
Significant Extent ◽  
Energy Surfaces ◽  
Transfer Potential

<div>The performance of spin-component scaled variants of the popular CC2 and ADC(2) methods is evaluated for CT states, following benchmark strategies of earlier studies. The results show the capability of spin-component scaled approaches to reduce the large errors of their regular counterparts to a significant extent.</div>

scholarly journals Improved Description of Charge Transfer Potential Energy Surfaces via Spin-Component Scaled CC2 and ADC(2) Methods

2020 ◽  
Author(s):  
Attila Tajti ◽  
Balázs Kozma ◽  
Péter Szalay
Keyword(s):  
Charge Transfer ◽  
Potential Energy ◽  
Potential Energy Surfaces ◽  
Spin Component ◽  
Significant Extent ◽  
Energy Surfaces ◽  
Transfer Potential

<div>The performance of spin-component scaled variants of the popular CC2 and ADC(2) methods is evaluated for CT states, following benchmark strategies of earlier studies. The results show the capability of spin-component scaled approaches to reduce the large errors of their regular counterparts to a significant extent.</div>

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