Toward accurate prediction of potential energy surfaces and the spectral density of hydrogen bonded systems

2014 ◽  
Vol 436 ◽  
pp. 164-176 ◽  
Author(s):  
Najeh Rekik
Keyword(s):  
Potential Energy ◽  
Spectral Density ◽  
Potential Energy Surfaces ◽  
Accurate Prediction ◽  
Hydrogen Bonded Systems ◽  
Energy Surfaces ◽  
Hydrogen Bonded

scholarly journals Theoretical Studies of Dynamic Interactions in Excited States of Hydrogen-Bonded Systems

2012 ◽  
Vol 2012 ◽  
pp. 1-17 ◽  
Author(s):  
Marek J. Wójcik ◽  
Marek Boczar ◽  
Łukasz Boda
Keyword(s):  
Hydrogen Bonds ◽  
Potential Energy ◽  
Benzoic Acid ◽  
Excited States ◽  
Potential Energy Surfaces ◽  
Low Frequency ◽  
Fermi Resonance ◽  
Tunneling Splittings ◽  
Energy Surfaces ◽  
Hydrogen Bonded

Theoretical model for vibrational interactions in the hydrogen-bonded benzoic acid dimer is presented. The model takes into account anharmonic-type couplings between the high-frequency O–H and the low-frequency O⋯O stretching vibrations in two hydrogen bonds, resonance interactions between two hydrogen bonds in the dimer, and Fermi resonance between the O–H stretching fundamental and the first overtone of the O–H in-plane bending vibrations. The model is used for theoretical simulation of the O–H stretching IR absorption bands of benzoic acid dimers in the gas phase in the first excited singlet state. Ab initio CIS and CIS(D)/CIS/6-311++G(d,p) calculations have been carried out in the à state of tropolone. The grids of potential energy surfaces along the coordinates of the tunneling vibration and the low-frequency coupled vibration have been calculated. Two-dimensional model potentials have been fitted to the calculated potential energy surfaces. The tunneling splittings for vibrationally excited states have been calculated and compared with the available experimental data. The model potential energy surfaces give good estimation of the tunneling splittings in the vibrationally ground and excited states of tropolone, and explain monotonic decrease in tunneling splittings with the excitation of low-frequency out-of-plane modes and increase of the tunneling splittings with the excitation of low-frequency planar modes.

scholarly journals Deconstructing Vibrational Motions on the Potential Energy Surfaces of Hydrogen-Bonded Complexes

CCS Chemistry ◽  
2021 ◽  
Vol 3 (1) ◽  
pp. 829-835 ◽  
Author(s):  
Bingbing Zhang ◽  
Shuo Yang ◽  
Qian-Rui Huang ◽  
Shukang Jiang ◽  
Rongjun Chen ◽  
...  
Keyword(s):  
Potential Energy ◽  
Potential Energy Surfaces ◽  
Energy Surfaces ◽  
Bonded Complexes ◽  
Hydrogen Bonded

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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