Estimation of ground and excited states dipole moments of α-hydroxy phenyl hydrazone derivatives: Experimental and quantum chemical methods

2014 ◽  
Vol 197 ◽  
pp. 386-394 ◽  
Author(s):  
İsa Sıdır ◽  
Yadigar Gülseven Sıdır ◽  
Ferhat Demiray ◽  
Halil Berber
Keyword(s):  
Excited States ◽  
Quantum Chemical ◽  
Dipole Moments ◽  
Chemical Methods ◽  
Quantum Chemical Methods

Tautomerism in Five-membered Nitrogen Heterocycles. A Test of the Reliability of Semiempirical (AMI, PM3, MNDO) Quantum Chemical Methods

1990 ◽  
Vol 45 (11-12) ◽  
pp. 1328-1334 ◽  
Author(s):  
Walter M. F. Fabian
Keyword(s):  
Quantum Chemical ◽  
Dipole Moments ◽  
Nitrogen Heterocycles ◽  
Ionization Potentials ◽  
Semiempirical Methods ◽  
Chemical Methods ◽  
Pm3 Method ◽  
Lone Pairs ◽  
Quantum Chemical Methods ◽  
The Stability

AbstractThe reliability of three popular semiempirical quantum chemical methods (AM1, PM3, MNDO) for the treatment of tautomeric equilibria is tested in a series of five-membered nitrogen heterocycles. The known flaw of MNDO to overestimate the stability of compounds with two or more adjacent pyridine-like lone pairs is also present in AM1 and to a somewhat lesser extent in PM3. Tautomeric species differing in the number of adjacent pyridine-like lone pairs, thus, cannot be adequately treated by these semiempirical methods. Both AM1 as well as PM3, however, represent major improvements over MNDO in the case of lactam-lactim tautomerism. The stability of N-oxides as compared to N-hydroxy tautomers seems to be overestimated by the PM3 method. All three semiempirical methods yield quite reliable ionization potentials and dipole moments.

Study of some aliphatic ammonium ylides by semiempirical and ab initio methods: Structure and charge distribution

1980 ◽  
Vol 45 (1) ◽  
pp. 92-103 ◽  
Author(s):  
Vladimír Král ◽  
Zdeněk Arnold
Keyword(s):  
Ab Initio ◽  
Charge Distribution ◽  
Quantum Chemical ◽  
Negative Charge ◽  
Dipole Moments ◽  
Ab Initio Methods ◽  
Chemical Methods ◽  
Quantum Chemical Methods

Structure of, and charge distribution in, some aliphatic ammonium ylides were determined by quantum chemical methods (CNDO/2, INDO, MINDO/2, PCILO, ab initio-STO-3G and 4-31G bases). Non-stabilized ylides were found to have pyramidal arrangement of bonds on the ylide carbon whereas the stabilized ylides have a planar arrangement. The charge distribution in stabilized ylides indicates a significant transfer of the negative charge from the ylide carbon to the electronegative groups. The calculated dipole moments for the previously prepared compounds, as well as for the derivatives VII and X, described in this paper, agree well with the experimental value.

scholarly journals Energetic Degeneracy and Electronic Structures of Germanium Trimers Doped with Titanium

2020 ◽  
Author(s):  
Le Nhan Pham ◽  
Salvy P. Russo
Keyword(s):  
Experimental Data ◽  
Excited States ◽  
Electronic Structures ◽  
Quantum Chemical ◽  
Electronic Transitions ◽  
Chemical Methods ◽  
Quantum Chemical Methods ◽  
Experimental Group ◽  
Comparison With Experimental Data

Several quantum chemical methods including CASSCF/CASPT2, CCSD(T)-F12, and DFT were used to study electronic structures and excited states of germanium trimers singly doped with titanium. All necessary parameters and calculations process are reported in the text. The conclusion on electronic transitions causing anion photoelectron bands was made by analysis of electronic structures and comparison with experimental data (reported by an experimental group).

scholarly journals Ab initio Calculations of Absorption Coefficients of Small Carbon Hydride Molecules

1994 ◽  
Vol 146 ◽  
pp. 326-337
Author(s):  
S.D. Peyerimhoff
Keyword(s):  
Electronic Structure ◽  
Ab Initio Calculations ◽  
Small Molecules ◽  
Excited States ◽  
Quantum Chemical ◽  
Special Importance ◽  
Absorption Coefficients ◽  
Chemical Methods ◽  
Theoretical Methods ◽  
Quantum Chemical Methods

Quantum chemical methods have become a powerful tool for investigating the electronic structure of small molecules in ground and excited states. This is particularly true for species which are not easily accessible by experiment, either because they are short-lived, for example, or unstable under laboratory conditions or difficult to detect since their signals are hidden by other, prevailing molecules. In this sense theoretical methods are of special importance for molecules in atmospheric, stellar and interstellar environments.

scholarly journals Energetic Degeneracy and Electronic Structures of Germanium Trimers Doped with Titanium

2020 ◽  
Author(s):  
Le Nhan Pham ◽  
Salvy P. Russo
Keyword(s):  
Experimental Data ◽  
Excited States ◽  
Electronic Structures ◽  
Quantum Chemical ◽  
Electronic Transitions ◽  
Chemical Methods ◽  
Quantum Chemical Methods ◽  
Experimental Group ◽  
Comparison With Experimental Data

Several quantum chemical methods including CASSCF/CASPT2, CCSD(T)-F12, and DFT were used to study electronic structures and excited states of germanium trimers singly doped with titanium. All necessary parameters and calculations process are reported in the text. The conclusion on electronic transitions causing anion photoelectron bands was made by analysis of electronic structures and comparison with experimental data (reported by an experimental group).

scholarly journals Energetics of LOHC: Structure-Property Relationships from Network of Thermochemical Experiments and in Silico Methods

Hydrogen ◽  
2021 ◽  
Vol 2 (1) ◽  
pp. 101-121
Author(s):  
Sergey P. Verevkin ◽  
Vladimir N. Emel’yanenko ◽  
Riko Siewert ◽  
Aleksey A. Pimerzin
Keyword(s):  
In Silico ◽  
Quantum Chemical ◽  
Structure Property ◽  
Chemical Methods ◽  
Key Technology ◽  
Structure Property Relationships ◽  
Quantum Chemical Methods ◽  
Dehydrogenation Reactions ◽  
Storage Technologies ◽  
In Silico Methods

The storage of hydrogen is the key technology for a sustainable future. We developed an in silico procedure, which is based on the combination of experimental and quantum-chemical methods. This method was used to evaluate energetic parameters for hydrogenation/dehydrogenation reactions of various pyrazine derivatives as a seminal liquid organic hydrogen carriers (LOHC), that are involved in the hydrogen storage technologies. With this in silico tool, the tempo of the reliable search for suitable LOHC candidates will accelerate dramatically, leading to the design and development of efficient materials for various niche applications.

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