scholarly journals Pseudo Jahn−Teller Origin of the Proton Tunneling in Zundel Cation Containing Water Clusters

2021 ◽  
Vol 57 (11) ◽  
pp. 1149
Author(s):  
I. Geru ◽  
N. Gorinchoy ◽  
I. Balan
Keyword(s):  
Ab Initio ◽  
Electronic Structures ◽  
Water Clusters ◽  
Electronic States ◽  
Adiabatic Potential ◽  
Water Molecules ◽  
High Symmetry ◽  
Proton Tunneling ◽  
Jahn Teller ◽  
Low Symmetry

The pseudo Jahn–Teller (PJT) origin of the proton transfer barrier in the Zundel cation at different O–O distances and in an H5O2+(H2O)4 cluster is revealed by means of  ab initio calculations of their electronic structures and the adiabatic potential energy curves. The vibronic constants in this approach were estimated by fitting the ab initio calculated adiabatic potential to its analytical expression. It is shown also that the high-symmetry nuclear configurations ofproton-centered water clusters of the type H+(H2O)n (n = 6, 4, 3) are unstable with respect to the low-symmetry nuclear distortions leading to forming the dihydronium cation H5O2+ and the appropriate number of water molecules: H2n + 1On+ →  (n – 2)H2O + H5O2+. The reason for this instability and the subsequent decay is the PJT coupling between the ground and excited electronic states.

scholarly journals Nucleus-independent chemical shift profiles along the intrinsic distortion path for Jahn-Teller active molecules. Study on cyclopentadienyl radical and cobaltocene

2015 ◽  
Vol 80 (7) ◽  
pp. 877-888 ◽  
Author(s):  
Ljubica Andjelkovic ◽  
Marko Peric ◽  
Matija Zlatar ◽  
Maja Gruden-Pavlovic
Keyword(s):  
Density Functional ◽  
Chemical Shifts ◽  
High Symmetry ◽  
Functional Theory ◽  
Aromatic Character ◽  
Nucleus Independent Chemical Shift ◽  
Jahn Teller ◽  
Cyclopentadienyl Radical ◽  
Cyclopentadienyl Anion ◽  
Low Symmetry

The aromatic/antiaromatic behavior of the cyclopentadienyl anion (Cp-), bis(?5-cyclopentadienyl)iron(II) (Fe(Cp)2), as well as of the Jahn-Teller (JT) active cyclopentadienyl radical (Cp?) and bis(?5-cyclopentadienyl)cobalt(II) (Co(Cp)2) has been investigated using Density Functional Theory (DFT) calculations of the Nuclear Independent Chemical Shifts (NICS). According to the NICS values, pentagon ring in Fe(Cp)2 is more aromatic than isolated Cp-. The NICS parameters have been scanned along the Intrinsic Distortion Path (IDP) for Cp? and Co(Cp)2 showing antiaromaticity, which decreases with increasing deviation from high symmetry D5h to low symmetry (LS) C2v. Changes in the NICS values along the IDP revealed that Co(Cp)2 in the LS nuclear arrangement has aromatic character, in contrast to the case of Cp?

AB Initio Simulation on Grotthuss Mechanism

2005 ◽  
Author(s):  
Jiahua Han ◽  
Hongtan Liu
Keyword(s):  
Ab Initio ◽  
Water Clusters ◽  
Dominant Role ◽  
High Mobility ◽  
Weight Fraction ◽  
Solvation Shell ◽  
Water Molecules ◽  
Proton Diffusion ◽  
Ab Initio Simulations ◽  
Grotthuss Mechanism

Ab initio simulations on Grotthuss mechanism have been carried out. Using the simulation results together with the existing experimental data, all the popular propositions for Grotthuss mechanism, including the one recently proposed by Noam [1], have been checked. Combining with the charge distribution calculation and the movement of the positive charge center inside the protonated water cluster during the proton diffusion process, only one mechanism is shown probable, while all the other proposed mechanisms are excluded. According to this probable mechanism, the high mobility of proton inside water is caused by the high diffusion rate of H5O2+, while the diffusion of H5O2+ is mainly induced by the thermal movement of water molecules at the second solvation shell of H5O2+ cation and the Zundel polarization inside the cation ion. Furthermore, the external field and thermo-dynamic effects play important roles during the transport process by affecting the reorientation of water molecules at the neighborhood of the second solvation shell of H5O2+ to induce the Zundel polarization and by providing the energy for the cleavage of the hydrogen bond between a newly formed water molecule and H5O2+. Because the weight (fraction) of H5O2+ among protonated water clusters decreases as temperature increases, this proposed mechanism is considered to play the dominant role only when temperature is below 572 K, above which, protons transport by other mechanisms become dominant.

Morphologies and Related Electronic Properties of Carbon Nanotubes

1998 ◽  
Vol 13 (9) ◽  
pp. 2368-2379 ◽  
Author(s):  
J-C. Charlier
Keyword(s):  
Carbon Nanotubes ◽  
Solid State ◽  
Structural Optimization ◽  
Ab Initio ◽  
Electronic Properties ◽  
Graphene Sheet ◽  
Electronic Structures ◽  
Tight Binding ◽  
Electronic States

The electronic structures of different morphologies of carbon nanotubes are investigated within either tight-binding or ab initio frameworks. After a brief description of the electronic properties of the “perfect” rolled-up graphene sheet, nanotubes containing pentagon-heptagon pairs, tips (hemispherical caps), sp3-like lines responsible for polygonization, multishell and solid-state packings (bundles) are studied in order to point out the influence of such defects on the electronic states of the “perfect” cylinders. Most of the time, a structural optimization was performed on the atomic topology, prior to the calculation of the electronic properties. Connections with experimental facts are indicated as frequently as possible.

scholarly journals Vibronic Origin of the “SKEWED” Anticline Configuration of the Hydrogen Peroxide Molecule

2008 ◽  
Vol 3 (1) ◽  
pp. 105-111
Author(s):  
N. N. Gorinchoy ◽  
I. Ya. Ogurtsov ◽  
Ion Arsene
Keyword(s):  
Hydrogen Peroxide ◽  
Electronic Structure ◽  
Potential Energy ◽  
Ab Initio Calculations ◽  
Ab Initio ◽  
Adiabatic Potential ◽  
Potential Energy Curves ◽  
High Symmetry ◽  
Analytical Expression ◽  
Peroxide Molecule

The vibronic origin of instability of the symmetrical forms (D¥ h, C2h and C2v) of the hydrogen peroxide molecule H2O2 was revealed using ab initio calculations of the electronic structure and the adiabatic potential energy curves. The vibronic constants in this approach were estimated by fitting of the ab initio calculated adiabatic potential in the vicinity of the high-symmetry nuclear configurations to its analytical expression. It was shown that the equilibrium “skewed” anticline shape of the C2 symmetry can be realized in two ways: D¥h ® C2v® C2 or D¥h ® C2h® C2 with the decreasing of the adiabatic potential energy at every step.

Blue absorption and red emission of Bi2+ in solids: strongly spin–orbit coupled 6p levels in low symmetry fields

2014 ◽  
Vol 16 (32) ◽  
pp. 17305-17314 ◽  
Author(s):  
Luis Seijo ◽  
Zoila Barandiarán
Keyword(s):  
Ab Initio ◽  
Radiative Lifetime ◽  
Orbit Coupling ◽  
Oscillator Strengths ◽  
High Symmetry ◽  
Spin Orbit Coupling ◽  
Spin Orbit ◽  
Red Emission ◽  
Confinement Potential ◽  
Low Symmetry

Ab initio calculations on a (BiO8)14− cluster under the effects of a high symmetry Oh confinement potential are used to study the energies of the 2P1/2, 2P3/2(1), and 2P3/2(2) spin–orbit coupling levels of the 6s26p configuration of Bi2+ in Oh, D4h, D2h, D4, D2d, D2, S4, C4v, C4, C3v, C2v, C2, Cs, and C1 fields, together with the 2P1/2 → 2P3/2(1) and 2P1/2 → 2P3/2(2) absorption oscillator strengths and the 2P3/2(1) radiative lifetime.

scholarly journals Predissociation resonances and accurate ab initio calculations of dication HF2+

RSC Advances ◽  
2021 ◽  
Vol 11 (16) ◽  
pp. 9600-9607
Author(s):  
Dong Liu ◽  
Rui Li ◽  
Juan Ren ◽  
Yongjun Cheng ◽  
Bing Yan ◽  
...  
Keyword(s):  
Ab Initio Calculations ◽  
Ab Initio ◽  
Bound States ◽  
Electronic States ◽  
Adiabatic Potential ◽  
Potential Curves

Highly accurate adiabatic potential curves of the 36 electronic states of the HF2+ dication by MRCI calculations. Panels (a), (b) and (c) correspond to the 16 singlet, 15 triplet and 4 quintet states, respectively. The nine bound states are highlighted and given in panel (d).

The hydration mechanism of ketene: 15 years later

1999 ◽  
Vol 77 (5-6) ◽  
pp. 817-829 ◽  
Author(s):  
Minh Tho Nguyen ◽  
Greet Raspoet
Keyword(s):  
Ab Initio ◽  
Gas Phase ◽  
Water Clusters ◽  
Field Method ◽  
Polarizable Continuum Model ◽  
Water Molecules ◽  
Orbital Theory ◽  
Acid Product ◽  
Reaction Field ◽  
Hydration Mechanism

New insights into the detailed mechanism of the hydration of ketene yielding acetic acid (H2C=C=O + H2O →> CH3COOH) were obtained by theoretical methods in both gas phase and solution. While gas phase calculations were performed using ab initio molecular orbital theory, bulk solvent effects were included using the self-consistent reaction field method (SCRF) and the polarizable continuum model (PCM). The hydration modeled by attack of water clusters containing two, three, and four water molecules confirms that a two-step addition of water to the ketene C=O bond, yielding a 1,1-enediol intermediate as initially demonstrated in 1984, is energetically, slightly but consistently, preferred over a concerted addition across the C=C bond leading directly to the acid product. Attempts to locate a zwitterion intermediate in solution were not successful. At least a cluster of three hydrogen-bonded water molecules is present in the gas phase supersystem to facilitate the proton transfer. Further incorporation of active water molecules in the catalytic water chain induces rather minor energetic improvements on the proton relay, which indicates a certain saturation of the cluster when reaching 3-4 water molecules. Effects of the surrounding solvent bulk do not change qualitatively the facts found in gas phase. The C=O addition mechanism is in better agreement with recent experimental developments in identifying enols of carboxylic acids than other mechanisms involving either a zwitterion or a direct C=C addition, as proposed for years in the literature.Key words: ketene, ketene hydration, hydration mechanism, solvent effect, ab initio calculations.

Calculation of Energy Levels of Cerium in Inorganic Scintillator Crystals

1994 ◽  
Vol 348 ◽  
Author(s):  
J. Andriessen ◽  
P. Dorenbos ◽  
C.W.E. van Eijk
Keyword(s):  
Ab Initio Calculations ◽  
Ab Initio ◽  
Energy Gap ◽  
Energy Levels ◽  
Fair Agreement ◽  
High Symmetry ◽  
Inorganic Scintillator ◽  
Low Symmetry

ABSTRACTFully relativistic ab initio calculations have been performed on energy levels of cerium in BaF2, LaF3, YAP and YAG. Also nonrelativistic calculations were done on cerium in LSO. The results are in fair agreement with experiment. Both the splitting of the 4f and 5d levels and the 4f–5d energy gap can be explained in the high symmetry crystal BaF2 as well as in the low symmetry crystals LaF3, YAP, YAG and LSO.

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