Global Reaction Route Mapping on Potential Energy Surfaces of Formaldehyde, Formic Acid, and Their Metal-Substituted Analogues

2006 ◽  
Vol 110 (28) ◽  
pp. 8933-8941 ◽  
Author(s):  
Koichi Ohno ◽  
Satoshi Maeda
Keyword(s):  
Potential Energy ◽  
Formic Acid ◽  
Potential Energy Surfaces ◽  
Reaction Route ◽  
Global Reaction ◽  
Energy Surfaces

scholarly journals Exploring Multiple Potential Energy Surfaces: Photochemistry of Small Carbonyl Compounds

2012 ◽  
Vol 2012 ◽  
pp. 1-13 ◽  
Author(s):  
Satoshi Maeda ◽  
Koichi Ohno ◽  
Keiji Morokuma
Keyword(s):  
Potential Energy ◽  
Carbonyl Compounds ◽  
Potential Energy Surfaces ◽  
Reaction Path ◽  
Photochemical Reactions ◽  
Reaction Route ◽  
Path Search ◽  
Global Reaction ◽  
Energy Surfaces ◽  
Critical Regions

In theoretical studies of chemical reactions involving multiple potential energy surfaces (PESs) such as photochemical reactions, seams of intersection among the PESs often complicate the analysis. In this paper, we review our recipe for exploring multiple PESs by using an automated reaction path search method which has previously been applied to single PESs. Although any such methods for single PESs can be employed in the recipe, the global reaction route mapping (GRRM) method was employed in this study. By combining GRRM with the proposed recipe, all critical regions, that is, transition states, conical intersections, intersection seams, and local minima, associated with multiple PESs, can be explored automatically. As illustrative examples, applications to photochemistry of formaldehyde and acetone are described. In these examples as well as in recent applications to other systems, the present approach led to discovery of many unexpected nonadiabatic pathways, by which some complicated experimental data have been explained very clearly.

Analytical Gradients for Core-Excited States in the Algebraic Diagrammatic Construction (ADC) Framework

2021 ◽  
Author(s):  
Iulia Emilia Brumboiu ◽  
Dirk R. Rehn ◽  
Andreas Dreuw ◽  
Young Min Rhee ◽  
Patrick Norman
Keyword(s):  
Excited State ◽  
Potential Energy ◽  
Formic Acid ◽  
Excited States ◽  
Potential Energy Surfaces ◽  
The Core ◽  
Energy Surfaces ◽  
Analytical Expressions ◽  
Analytical Gradients ◽  
Optimized Geometries

Here we present a derivation of the analytical expressions required to determine nuclear gradients for core-excited states at the core-valence separated algebraic diagrammatic construction (CVS-ADC) theory level. Analytical gradients up to and including the extended CVS-ADC(2)-x order have been derived and implemented into a Python module, adc_gradient. The gradients were used to determine core-excited state optimized geometries and relaxed potential energy surfaces for the water, formic acid, and benzne molecules. <br>

Analytical Gradients for Core-Excited States in the Algebraic Diagrammatic Construction (ADC) Framework

2021 ◽  
Author(s):  
Iulia Emilia Brumboiu ◽  
Dirk R. Rehn ◽  
Andreas Dreuw ◽  
Young Min Rhee ◽  
Patrick Norman
Keyword(s):  
Excited State ◽  
Potential Energy ◽  
Formic Acid ◽  
Excited States ◽  
Potential Energy Surfaces ◽  
The Core ◽  
Energy Surfaces ◽  
Analytical Expressions ◽  
Analytical Gradients ◽  
Optimized Geometries

Here we present a derivation of the analytical expressions required to determine nuclear gradients for core-excited states at the core-valence separated algebraic diagrammatic construction (CVS-ADC) theory level. Analytical gradients up to and including the extended CVS-ADC(2)-x order have been derived and implemented into a Python module, adc_gradient. The gradients were used to determine core-excited state optimized geometries and relaxed potential energy surfaces for the water, formic acid, and benzne molecules. <br>

Resolving the Quadruple Bonding Conundrum in C2 Using Insights Derived from Excited State Potential Energy Surfaces: A Molecular Orbital Perspective

2019 ◽  
Author(s):  
Ishita Bhattacharjee ◽  
Debashree Ghosh ◽  
Ankan Paul
Keyword(s):  
Excited State ◽  
Potential Energy ◽  
Molecular Orbital ◽  
High Spin ◽  
Potential Energy Surfaces ◽  
Valence Bond ◽  
Deep Minimum ◽  
State Potential ◽  
Energy Surfaces ◽  
Mo Theory

The question of quadruple bonding in C<sub>2</sub> has emerged as a hot button issue, with opinions sharply divided between the practitioners of Valence Bond (VB) and Molecular Orbital (MO) theory. Here, we have systematically studied the Potential Energy Curves (PECs) of low lying high spin sigma states of C<sub>2</sub>, N<sub>2</sub> and Be<sub>2</sub> and HC≡CH using several MO based techniques such as CASSCF, RASSCF and MRCI. The analyses of the PECs for the<sup> 2S+1</sup>Σ<sub>g/u</sub> (with 2S+1=1,3,5,7,9) states of C<sub>2</sub> and comparisons with those of relevant dimers and the respective wavefunctions were conducted. We contend that unlike in the case of N<sub>2</sub> and HC≡CH, the presence of a deep minimum in the <sup>7</sup>Σ state of C<sub>2</sub> and CN<sup>+</sup> suggest a latent quadruple bonding nature in these two dimers. Hence, we have struck a reconciliatory note between the MO and VB approaches. The evidence provided by us can be experimentally verified, thus providing the window so that the narrative can move beyond theoretical conjectures.

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