Computational studies of the cationic aluminium(chloro) hydroxides by quantum chemical ab initio methods

2005 ◽  
Vol 7 (22) ◽  
pp. 3785 ◽  
Author(s):  
Jaakko Saukkoriipi ◽  
Atte Sillanpää ◽  
Kari Laasonen
Keyword(s):  
Ab Initio ◽  
Quantum Chemical ◽  
Computational Studies ◽  
Ab Initio Methods

scholarly journals Quantum-chemical calculations of the products and energies of electron induced ionization of 2-Furanmethanol, Tetrahydro-and 3-Furanol

2008 ◽  
Vol 6 (1) ◽  
pp. 127-139 ◽  
Author(s):  
P. Papp ◽  
P. Mach ◽  
J. Urban ◽  
S. Matejcík
Keyword(s):  
Ab Initio ◽  
Electron Impact ◽  
Quantum Chemical Calculations ◽  
Quantum Chemical ◽  
Impact Ionization ◽  
Theoretical Treatment ◽  
Ab Initio Methods ◽  
Conformational Studies ◽  
Fragmentation Patterns

A theoretical treatment is used to perform conformational studies of title compounds, which was previously successfully used within our group for characterization of fragmentation patterns of some bio-molecules. Now we present studies of electron impact ionization of 2 Furanmethanol, Tetrahydro (C5H10O2) and 3-Furanol, Tetrahydro (C4H8O2), both as important models for more complicated compounds like nucleic acids. In this paper geometry of the neutral and cationic conformers of these two molecules was optimized on the DFT level with B3LYP functional, and ionization energies were estimated. DFT calculated results are supplemented with G3MP2 calculations, and a set of higher-level ab initio methods were empirically corrected to obtain more reliable results.

Computational Photobiology and Beyond

2010 ◽  
Vol 63 (3) ◽  
pp. 413 ◽  
Author(s):  
Igor Schapiro ◽  
Mikhail N. Ryazantsev ◽  
Wan Jian Ding ◽  
Mark M. Huntress ◽  
Federico Melaccio ◽  
...  
Keyword(s):  
Quantum Mechanics ◽  
Excited State ◽  
Ab Initio ◽  
Molecular Mechanics ◽  
Chemical Treatment ◽  
Quantum Chemical ◽  
Organic Molecules ◽  
Molecular Devices ◽  
Computational Studies ◽  
Computational Investigation

In this paper we review the results of a group of computational studies of the spectroscopy and photochemistry of light-responsive proteins. We focus on the use of quantum mechanics/molecular mechanics protocols based on a multiconfigurational quantum chemical treatment. More specifically, we discuss the use, limitations, and application of the ab initio CASPT2//CASSCF protocol that, presently, constitutes the method of choice for the investigation of excited state organic molecules, most notably, biological chromophores and fluorophores. At the end of this Review we will also see how the computational investigation of the visual photoreceptor rhodopsin is providing the basis for the design of light-driven artificial molecular devices.

QUANTUM CHEMICAL STUDY OF POLYAROMATIC HYDROCARBONS IN HIGH MULTIPLICITY STATES

2007 ◽  
Vol 21 (26) ◽  
pp. 4507-4515 ◽  
Author(s):  
VOLODYMYR D. KHAVRYUCHENKO ◽  
YURIJ A. TARASENKO ◽  
VOLODYMYR V. STRELKO ◽  
OLEKSIY V. KHAVRYUCHENKO ◽  
VLADYSLAV V. LISNYAK
Keyword(s):  
Ab Initio ◽  
Electronic Structures ◽  
Quantum Chemical ◽  
Polyaromatic Hydrocarbons ◽  
Quantum Chemical Study ◽  
Chemical Study ◽  
High Multiplicity ◽  
Ab Initio Methods ◽  
Energetic Stability

A study of polyaromatic hydrocarbons by semiempirical PM3 and ab initio methods in MINI and STO 6G-31 bases has been performed for compounds with different numbers of rings. The optimized space and electronic structures have been derived. The multiplicity states effect on the energetic stability of the polyaromatic hydrocarbons is examined. It is shown that the high multiplicity states become more energetically preferable with the growth of the PAH size.

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.

THERMOCHEMISTRY OF ORGANIC, HETEROORGANIC, AND INORGANIC MOLECULES AND THEIR FRAGMENTS: "QUANTUM-CHEMICAL CALCULATIONS OF THERMOCHEMICAL PARAMETERS: MOLECULES AND THEIR FRAGMENTS"

2010 ◽  
Vol 09 (supp01) ◽  
pp. 125-153 ◽  
Author(s):  
A. V. GOLOVIN ◽  
D. A. PONOMAREV ◽  
V. V. TAKHISTOV
Keyword(s):  
Free Radicals ◽  
Ab Initio ◽  
Quantum Chemical Calculations ◽  
Quantum Chemical ◽  
Enthalpies Of Formation ◽  
Ab Initio Methods ◽  
Isodesmic Reactions ◽  
Great Caution ◽  
Thermochemical Parameters ◽  
Inorganic Molecules

Analysis of theoretical enthalpies of formation for about 300 molecules and their fragments (free radicals, biradicals, and ions) was performed to show that the results of semiempirical, DFT, and ab initio methods must be taken with great caution. A brief review of the authors' alternative empirical methodologies for calculation of enthalpies of formation for molecules (enthalpic shift procedure) and free radicals (enthalpies of isodesmic reactions) is given.

Determination of acidic dissociation constants of L-phenylalanyl-glycine and L-alanyl-L-alanine in water using ab initio methods

2014 ◽  
Vol 2 (42) ◽  
pp. 263-263
Author(s):  
Farhoush Kiani ◽  
Mahmoud Tajbakhsh ◽  
Fereydoon Ashrafi ◽  
Nesa Shafiei ◽  
Azar Bahadori ◽  
...  
Keyword(s):  
Ab Initio ◽  
Dissociation Constants ◽  
Ab Initio Methods ◽  
Acidic Dissociation

Evaluation of Chemotherapeutic Activity of the Selected Bases’ Analogues of Nucleic Acids Supported by ab initio Various Quantum Chemical Calculations

2020 ◽  
Vol 16 (2) ◽  
pp. 93-103 ◽  
Author(s):  
Piotr Kawczak ◽  
Leszek Bober ◽  
Tomasz Bączek
Keyword(s):  
Biological Activity ◽  
Nucleic Acids ◽  
Ab Initio ◽  
Quantum Chemical Calculations ◽  
Quantum Chemical ◽  
Structural Parameters ◽  
Principal Component ◽  
Polarizable Continuum Model ◽  
Activity Data ◽  
Qsar Models

Background: Pharmacological and physicochemical classification of bases’ selected analogues of nucleic acids is proposed in the study. Objective: Structural parameters received by the PCM (Polarizable Continuum Model) with several types of calculation methods for the structures in vacuo and in the aquatic environment together with the huge set of extra molecular descriptors obtained by the professional software and literature values of biological activity were used to search the relationships. Methods: Principal Component Analysis (PCA) together with Factor Analysis (FA) and Multiple Linear Regressions (MLR) as the types of the chemometric approach based on semi-empirical ab initio molecular modeling studies were performed. Results: The equations with statistically significant descriptors were proposed to demonstrate both the common and differentiating characteristics of the bases' analogues of nucleic acids based on the quantum chemical calculations and biological activity data. Conclusion: The obtained QSAR models can be used for predicting and explaining the activity of studied molecules.

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