scholarly journals MgO Cluster Models for Capture CO2 Molecule

2020 ◽  
Vol 5 (8) ◽  
pp. 915-921
Author(s):  
Zinab Ibrahim Alhony ◽  
Fathi Hassan Bawa
Keyword(s):  
Density Functional ◽  
Dft Method ◽  
Binding Energies ◽  
Cluster Models ◽  
Basis Sets ◽  
Practical Applications ◽  
Adsorption Sites ◽  
Acidic Sites ◽  
Homo And Lumo ◽  
Carbonate Species

The density functional theory (DFT) method was used to study the adsorption of acidic CO2 molecule on the oxide clusters (MgO)n , (n = 2, 4, 6, 8, 9 and 12). Basis sets, 6–311 G, 6–311G (d) and 6–311G (2d) were employed in order to test the effect on adsorption structures and binding energies. Both  and adsorption sites have been considered. Our previous calculation DFT energies have been achieved for the (MgO)n, (CaO)n, (n = 1–4, 6, 8, 9, and 12 clusters), [WJERT, 2019, Vol.5, Issue 1, 328-341]. The present work investigates the adsorption properties (e.g., adsorption energies, geometries and HOMO and LUMO molecular orbitals) of a single CO2 molecule. The results show that the CO2 molecule / (MgO)n clusters prefer to adsorb as [Mg surf –  with one acidic sites, while the interaction with surface basic    sites, carbonate species consequently may occur. The HOMO and LUMO interaction between CO2 and MgO cluster models were also studied. Furthermore, such nanostructures systems can be potential candidates for practical applications of capturing CO2 from hot exhaust gases.

scholarly journals Vibrational Spectroscopic Investigation and Conformational Analysis of Methacrylamidoantipyrine: A Comparative Density Functional Study

2013 ◽  
Vol 2013 ◽  
pp. 1-10 ◽  
Author(s):  
Özgür Alver ◽  
Mehmet Fatih Kaya ◽  
Metin Bilge ◽  
Cemal Parlak
Keyword(s):  
Conformational Analysis ◽  
Density Functional ◽  
Dft Method ◽  
Basis Sets ◽  
Potential Energy Distribution ◽  
Functional Study ◽  
Stable Form ◽  
Vibrational Assignments ◽  
B3lyp Method ◽  
Homo And Lumo

FT-IR and Raman spectra of methacrylamidoantipyrine (MAAP) have been reported in the region of 4000–10 cm−1 and 4000–100 cm−1, respectively. The optimized geometric parameters, conformational analysis, normal mode frequencies, and corresponding vibrational assignments of MAAP (C15H17N3O2) have been examined by means of density functional theory (DFT) method using the Becke-3-Lee-Yang-Parr (B3LYP) exchange-correlation functional and the 6-31G++(d,p) basis sets. Vibrational assignments have been made on the basis of potential energy distribution (PED) and the thermodynamics functions, and the highest occupied and the lowest unoccupied molecular orbitals (HOMO and LUMO) of MAAP have been predicted. Calculations are carried out with the possible seven (amide-1–5 and imide-1-2) conformational isomers of MAAP. Comparison between the experimental and theoretical results indicates that the B3LYP method provides satisfactory evidence for the prediction of vibrational wavenumbers, and the amide-1 conformational isomer is supposed to be the most stable form of MAAP.

Quantum-Chemical Ab Initio Calculations on Inda- and Thallabenzene (C5H5In and C5H5Tl) and their Structural Isomers η5-C5H5In and η5-C5H5Tl

2018 ◽  
Vol 71 (3) ◽  
pp. 102
Author(s):  
Emma Persoon ◽  
Yuekui Wang ◽  
Gerhard Raabe
Keyword(s):  
Ab Initio ◽  
Quantum Chemical ◽  
Density Functional ◽  
Single Point ◽  
Normal Modes ◽  
Dft Method ◽  
Basis Sets ◽  
Triplet States ◽  
Structural Isomers ◽  
Td Dft

Quantum-chemical ab initio, time-independent, as well as time-dependent density functional theory (TD-DFT) calculations were performed on the so far elusive heterocycles inda- and thallabenzene (C5H5In and C5H5Tl), employing several different methods (MP2, CISD, CCSD, CCSD(T), BD, BD(T), QCISD, QCISD(T), CASSCF, DFT/B3LYP), effective core potentials, and different basis sets. While calculations on the MP2 level predict the ground states of the title compounds to be singlets with the first triplet states between 13 and 15 kcal mol−1 higher in energy, single point calculations with the QCISD(T), CCSD(T), and BD(T) methods at CCSD-optimized structures result in energy differences between the singlet and the triplet states in the range between 0.3 and 2.1 kcal mol−1 in favour of the triplet states. According to a CASSCF(8,8) calculation the triplets are also more stable by about 2.5–2.9 kcal mol−1. Calculations were also performed for the C5v-symmetric η5 structural isomers (cyclopentadienylindium, CpIn, and cyclopentadienylthallium, CpTl, Cp = C5H5) of the title compounds. At the highest level of theory employed in this study, C5H5In is between 79 and 88 kcal mol−1 higher in energy than CpIn, while this energy difference is even larger for thallabenzene where C5H5Tl is energetically between 94 and 102 kcal mol−1 above CpTl. In addition we report on the UV/vis spectra calculated with a TD-DFT method as well as on the spectra of the normal modes of C5H5In and C5H5Tl. Both types of spectra might facilitate identification of the title compounds eventually formed in photolysis or pyrolysis experiments.

scholarly journals Experimental and Density Functional Theory Characteristics of Ibrutinib, a Bruton’s Kinase Inhibitor Approved for Leukemia Treatment

2021 ◽  
Vol 2021 ◽  
pp. 1-8
Author(s):  
Ali I. Ismail
Keyword(s):  
Density Functional Theory ◽  
Density Functional ◽  
Kinase Inhibitor ◽  
Theoretical Calculations ◽  
Dft Method ◽  
Vibrational Frequencies ◽  
Basis Sets ◽  
Electronic Transitions ◽  
Functional Theory ◽  
Leukemia Treatment

Ibrutinib, a Bruton’s tyrosine kinase that plays an essential role in the B-cell development and cancer cells, has been recently approved to treat chronic, lymphocytic, and other types of leukemia. This study focused on investigating ibrutinib by its electronic transitions, vibrational frequencies, and electrospray mass spectra. The experimental peaks for electronic spectrum were found at 248.0 and 281.0 nm, whereas the νC = 0 stretching frequency was found at 1652.4 and 1639.19 cm−1. These experimental properties were compared with the corresponding theoretical calculations in which density functional theory was applied. The optimized structure was obtained with the calculations using a hybrid function (B3LYP) and high-level basis sets [6-311G++(d,p)]. Most of the calculated vibrational frequencies showed a relatively good agreement with the experimental ones. The electronic transitions of ibrutinib calculated using time-dependent DFT method were performed at two different solvation methods: PCM and SMD. The mass spectrum of ibrutinib, its fragments, and its isotopic pattern agreed well with the expected spectra.

A density functional approach toward structural features and properties of C20…N2X2 (X = H, F, Cl, Br, Me) molecules

2014 ◽  
Vol 13 (04) ◽  
pp. 1450023 ◽  
Author(s):  
Reza Ghiasi ◽  
Morteza Zaman Fashami ◽  
Amir Hossein Hakimioun
Keyword(s):  
Density Functional ◽  
Chemical Shifts ◽  
Geometry Optimization ◽  
Structural Features ◽  
Nbo Analysis ◽  
Basis Set ◽  
Basis Sets ◽  
Basis Set Superposition Error ◽  
Homo And Lumo ◽  
Lowest Unoccupied Molecular Orbitals

In this work, the interaction of C 20 with N 2 X 2 ( X = H , F , Cl , Br , Me ) molecules has been explored using the B3LYP, M062x methods and 6-311G(d,p) and 6-311+G(d,p) basis sets. The interaction energies (IEs) obtained with standard method were corrected by basis set superposition error (BSSE) during the geometry optimization for all molecules at the same levels of theory. It was found C 20… N 2 H 2 interaction is stronger than the interaction of other N 2 X 2 ( X = F , Cl , Br , Me ) with C 20. Highest occupied and lowest unoccupied molecular orbitals (HOMO and LUMO, respectively) levels are illustrated by density of states spectra (DOS). The nucleus-independent chemical shifts (NICSs) confirm that C 20… N 2 X 2 molecules exhibit aromatic characteristics. Geometries obtained from DFT calculations were used to perform NBO analysis. Also, 14 N NQR parameters of the C 20… N 2 X 2 molecules are predicted.

scholarly journals ABSORPTION OF SOME SMALL SILVER CLUSTERS: DFT AND CASPT2 CALCULATIONS

2018 ◽  
Vol 55 (6A) ◽  
pp. 72
Author(s):  
Ngo Tuan Cuong
Keyword(s):  
Absorption Spectra ◽  
Density Functional ◽  
Noble Gas ◽  
Silver Cluster ◽  
Dft Method ◽  
Basis Sets ◽  
Silver Clusters ◽  
Excitation Energies ◽  
Complete Active Space ◽  
Td Dft

Two quantum chemical methods which are the time-dependent density functional theory (TD-DFT) and the complete active space CASPT2/CASSCF have been used in modeling absorption spectra of silver clusters Agn (n = 2, 3, 4, 6, 8). There is an overall good agreement between TD-DFT and CASPT2 results for transition energies. The absorption spectra of the Agn clusters examined can reasonably be simulated using the excitation energies obtained by either TD-DFT or CASPT2 method.  The main result emerged from this calculation is that the TD-DFT method is suitable for treatment of excited states of Ag clusters. The choice of specific functionals and basis sets to be used in some cases induces important effects on the calculated spectra. It is also noteworthy to mention that for some clusters, the neutral Ag6 for instance, the effect of noble gas environment is significant, while for some others such as the neutral Ag8, it is not. Therefore, carrying out TD-DFT calculations to reproduce and to assign a given structure to an experimental absorption spectrum of a silver cluster, it is not only to select suitable functionals but also to take enough effects of environments into account. 

Geometry Optimization, UV/Vis, NBO, HOMO and LUMO, Excited State and Antioxidant Evaluation of Pyrimidine Derivatives

2020 ◽  
Vol 17 ◽  
Author(s):  
Siyamak Shahab ◽  
Masoome Sheikhi ◽  
Evgeni Kvasyuk ◽  
Aliaksei G. Sysa ◽  
Radwan Alnajjar ◽  
...  
Keyword(s):  
Density Functional ◽  
Antioxidant Properties ◽  
Geometry Optimization ◽  
Dft Method ◽  
Oscillator Strengths ◽  
Equilibrium Geometry ◽  
Pyrimidine Derivatives ◽  
Excitation Energies ◽  
Solvent Water ◽  
Homo And Lumo

: In this research, the four pyrimidine derivatives have been studied by using density functional theory (DFT/B3LYP/6-31G*) in solvent water for the first time. After quantum-chemical calculations, the title compounds have been synthesized. The electronic spectra of the new derivatives in a solvent water were performed by time-dependent DFT (TD-DFT) method. The equilibrium geometry, the HOMO and LUMO orbitals, MEP, excitation energies, natural charges, oscillator strengths for the molecules have also been calculated. NBO analysis has been calculated in order to elucidate the intramolecular, rehybridization and delocalization of electron density. These molecules have high antioxidant potential due to the planarity and formation of intramolecular hydrogen bonds. Antioxidant properties of the title compounds have been investigated and discussed.

Adsorption of rare-earth atoms onl silicon carbide nanotube: a density-functional study

2014 ◽  
Vol 28 (19) ◽  
pp. 1450154
Author(s):  
Zhiwei An ◽  
Jiang Shen
Keyword(s):  
Silicon Carbide ◽  
Rare Earth ◽  
Density Functional ◽  
Binding Energies ◽  
Functional Study ◽  
Hollow Site ◽  
Functional Theory ◽  
Adsorption Sites ◽  
Metal Atoms ◽  
Silicon Carbide Nanotube

In this paper, we investigate the adsorption of a series of rare-earth (RE) metal atoms ( La , Pr , Nd , Sm and Eu ) on the pristine zigzag (8, 0) silicon carbide nanotube ( SiCNT ) using density functional theory (DFT). Main focuses are placed on the stable adsorption sites, the corresponding binding energies, and the modified electronic properties of the SiC nanotubes due to the adsorbates. A single RE atom prefers to adsorb strongly at the hollow site with relatively high binding energy (larger than 1.0 eV). Due to the rolling effect of single-walled SiCNTs , the inside configurations are more stable than the outside ones. For RE-adsorbed systems, the adsorption of metal atoms induces certain impurity states within the band gap of the pristine SiCNT . Furthermore, we analyze there exists hybridizations between RE-5d, 6s, C -2p and Si -3p orbitals for the RE atom adsorption on the SiCNTs .

scholarly journals Theoretically nanoscale study on ionization of muscimol nano drug in aqueous solution

2015 ◽  
Vol 51 (1) ◽  
pp. 213-219 ◽  
Author(s):  
Farhoush Kiani ◽  
Mehran Abbaszadeh ◽  
Mohammad Pousti ◽  
Fardad Koohyar
Keyword(s):  
Density Functional ◽  
Dft Method ◽  
Acid Dissociation ◽  
Basis Sets ◽  
Acid Dissociation Constant ◽  
Functional Theory ◽  
Hydrogen Bond Formation ◽  
Pka Values ◽  
The Density Functional Theory ◽  
Good Agreement

In the present work, acid dissociation constant (pKa) values of muscimol derivatives were calculated using the Density Functional Theory (DFT) method. In this regard, free energy values of neutral, protonated and deprotonated species of muscimol were calculated in water at the B3LYP/6-31G(d) basis sets. The hydrogen bond formation of all species had been analyzed using the Tomasi's method. It was revealed that the theoretically calculated pKa values were in a good agreement with the existing experimental pKa values, which were determined from capillary electrophoresis, potentiometric titration and UV-visible spectrophotometric measurements.

What Silicon Nanocluster is Most Likely Formed in Etching Experiments? Theoretical DFT Study

2008 ◽  
Vol 8 (7) ◽  
pp. 3478-3482
Author(s):  
Nurbosyn U. Zhanpeisov ◽  
Hiroshi Fukumura
Keyword(s):  
Absorption Spectra ◽  
Density Functional Calculations ◽  
Density Functional ◽  
Electrochemical Etching ◽  
Time Dependent ◽  
Cluster Models ◽  
Dft Study ◽  
Basis Sets ◽  
Self Healing ◽  
Tddft Calculations

Density functional calculations at the B3LYP/6-31G* level were performed for Si nanoclusters of ca.1 nm in size. The structural, energetic, electronic as well as the estimated absorption spectra by the time-dependent DFT (TDDFT) calculations using varied functionals and basis sets for the representative cluster models are all in favor of the formation of most probable Si35H36 nanocluster in recent electrochemical etching experiments. The nanostructure has a complete H-termination at the borderline regions and lacks from the presence of any defects like surface Si—Si dimer units formed via self-healing of dangling Si—Si bonds or from any relatively short H…H contacts.

Theoretical study ofFeB35+nN36-n(n = 0, 1) nanocages: Chemical reactivity descriptors

2015 ◽  
Vol 14 (04) ◽  
pp. 1550026 ◽  
Author(s):  
Davood Farmanzadeh ◽  
Hamid Rezainejad
Keyword(s):  
Density Functional ◽  
Chemical Reactivity ◽  
Chemical Species ◽  
Dft Method ◽  
High Reactivity ◽  
Binding Energies ◽  
Functional Theory ◽  
Reactivity Descriptors ◽  
The Density Functional Theory ◽  
Chemical Reactivity Descriptors

In this study, by the density functional theory (DFT) method-based reactivity descriptors, the electronic properties and chemical reactivity of Fe substituted nanocage, FeB35+nN36-n(n = 0, 1), were investigated in gaseous and aqueous phases. The calculated binding energies of Fe atoms revealed that the substituting Fe atom in some locations of nanocage make the system more stable. The calculated global descriptors showed that the substituted Fe remarkably increases the chemical reactivity of B36N36. Also, local descriptors showed that the high reactivity of substituted nanocages is mainly related to Fe atom and these chemical species are more talented for nucleophilic attacks. The results of this work may be useful to investigate the effects of substituted metals in chemical reactivity of BN nanostructures.

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