Vibrationally resolved K-shell photoionization cross sections of methane

Open Physics ◽  
2013 ◽  
Vol 11 (9) ◽  
Author(s):  
Etienne Plésiat ◽  
Piero Decleva ◽  
Fernando Martín
Keyword(s):  
Cross Sections ◽  
Density Functional ◽  
Dft Method ◽  
Chem Phys ◽  
Angular Distributions ◽  
Functional Theory ◽  
The Rich ◽  
Photoelectron Angular Distributions ◽  
Molecular Frame ◽  
Good Agreement

AbstractWe use an extension of the static-exchange density functional theory (DFT) method, previously reported in [E. Plésiat et al., Phys. Rev. A 2, 023409 (2012), E. Plésiat, P. Decleva, F. Martín, Phys. Chem. Chem. Phys. 31, 10853 (2012)], to evaluate vibrationally resolved (total and angular) K-shell photoelectron cross sections of methane. The calculated cross sections are in very good agreement with the existing experimental measurements at low photoelectron energies. We show that, in contrast with the rich interference patterns previously observed in molecular frame C(1s) photoelectron angular distributions of methane at both low and high photoelectron energy, no interference effects are observed in the calculated β parameters, even at high photon energies.

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.

Simulation of porphyrin-ethanol solvate shell by DFT method

2015 ◽  
Vol 19 (11) ◽  
pp. 1212-1218 ◽  
Author(s):  
Pavel V. Singin ◽  
Mikhail K. Islyaikin ◽  
Irina P. Trifonova ◽  
Vladimir A. Burmistrov ◽  
Oscar I. Koifman
Keyword(s):  
Density Functional ◽  
Dft Method ◽  
Solvation Energy ◽  
Solvation Shell ◽  
Theoretical Studies ◽  
Functional Theory ◽  
H Nmr ◽  
Ethanol Solvate ◽  
Nucleophilic Solvation ◽  
Good Agreement

Theoretical studies on porphyrin-ethanol solvates containing from 1 to 8 ethanol molecules have been carried out by density functional theory (DFT) calculations using hybrid (B3LYP) and meta-GGA (M06-L) functionals. It was established that porphirin molecule can be considered as two centered protones acceptor. Specific solvation is at the base of porphyrin-(EtOH)n interactions and results in a distortion of macrocycle planar structure. The nucleophilic solvation energy of the porphirin pyrrole demonstrates dependence on the number of molecules in the ethanol solvate, being the highest for the first two ethanol molecules and decreasing with ethanol association in the solvation shell. Results obtained by this way are in good agreement with data derived from 1H NMR.

scholarly journals CO interaction with Cu(I)-MCM-22 zeolite: density functional theory investigation

2014 ◽  
Vol 17 (3) ◽  
pp. 19-29
Author(s):  
Ho Thang Viet ◽  
Petr Nachtigall
Keyword(s):  
Density Functional Theory ◽  
Density Functional ◽  
Co Adsorption ◽  
Dft Method ◽  
Local Geometry ◽  
Functional Theory ◽  
Two Peaks ◽  
Decomposition Of No ◽  
Good Agreement ◽  
Oxygen Atoms

MCM-22 zeolite has been widely used in many applications for catalysis and adsorption. Especially, this material exchanged with Cu+ cation (Cu(I)-MCM-22) is an active catalyst in green chemical reaction, such as decomposition of NO and N2O. The local geometry of Cu+ in vicinity of Al (III) replacement in six different Si (IV) sites and CO interaction with the most stable Cu+ in each Al site were explored using periodic density functional theory (DFT) method. The CO stretching frequencies were computed applying the ω/r scaling method in which frequencies were determined at high quantum level (couple cluster) and CO bond length calculated at DFT level. The results showed that Cu+ cation located in the channel wall position and intersection position coordinated with 3 or 2 framework oxygen atoms, respectively, before CO adsorption and Cu+ cation coordinated with 2 framework oxygen atoms after CO adsorption. The interaction energies between CO and Cu+ cation were in range - 148 to -195 kJ.mol-1 and CO frequencies exhibit two peaks at 2151 and 2159 cm-1 in good agreement with experimental data. This investigation brought us to understand the Cu+ location in MCM-22 and CO adsorption in Cu(I)-MCM-22 zeolite.

Synthesis of New α-Amino Phosphonates Containing 3-Amino-4(3H) Quinazolinone Moiety as Anticancer and Antimicrobial Agents: DFT, NBO, and Vibrational Studies

2018 ◽  
Vol 15 (2) ◽  
pp. 286-296 ◽  
Author(s):  
Mohamed K. Awad ◽  
Mahmoud F. Abdel-Aal ◽  
Faten M. Atlam ◽  
Hend A. Hekal
Keyword(s):  
Biological Activity ◽  
Cell Line ◽  
Quantum Chemical ◽  
Density Functional ◽  
Carcinoma Cell ◽  
Liver Carcinoma ◽  
Anticancer Activities ◽  
Functional Theory ◽  
Ft Ir ◽  
Good Agreement

Aim and Objective: Synthesis of new .-aminophosphonates containing quinazoline moiety through Kabachnik-Fields reaction in the presence of copper triflate catalyst [32], followed by studying their antimicrobial activities and in vitro anticancer activities against liver carcinoma cell line (HepG2) with the hope that new anticancer agents could be developed. Also, the quantum chemical calculations are performed using density functional theory (DFT) to study the effect of the changes of molecular and electronic structures on the biological activity of the investigated compounds. Materials and Method: The structures of the synthesized compounds are confirmed by FT-IR, 1H NMR, 13C NMR, 31P NMR and MS spectral data. The synthesized compounds show significant antimicrobial and also remarkable cytotoxicity anticancer activities against liver carcinoma cell line (HepG2). Density functional theory (DFT) was performed to study the effect of the molecular and electronic structure changes on the biological activity. Results: It was found that the electronic structure of the substituents affects on the reaction yield. The electron withdrawing substituent, NO2 group 3b, on the aromatic aldehydes gave a good yield more than the electron donating substituent, OH group 3c. The electron deficient on the carbon atom of the aldehydic group may increase the interaction of the Lewis acid (Cu(OTf)2) and the Lewis base (imine nitrogen), and accordingly, facilitate the formation of imine easily, which is attacked by the nucleophilic phosphite species to give the α- aminophosphonates. Conclusion: The newly synthesized compounds exhibit a remarkable inhibition of the growth of Grampositive, Gram-negative bacteria and fungi at low concentrations. The cytotoxicity of the synthesized compounds showed a significant cytotoxicity against the liver cancer cell line (HepG 2). Also, it was shown from the quantum chemical calculations that the electron-withdrawing substituent increases the biological activity of the α-aminophosphonates more than the electron donating group which was in a good agreement with the experimental results. Also, a good agreement between the experimental FT-IR and the calculated one was found.

Understanding the molecular mechanism of the stereoselective conversion of N-trialkylsilyloxy nitronates into bicyclic isoxazoline derivatives

2021 ◽  
Author(s):  
Agnieszka Kącka-Zych ◽  
Radomir Jasinski
Keyword(s):  
Density Functional Theory ◽  
Molecular Mechanism ◽  
Electron Density ◽  
Density Functional ◽  
Dft Method ◽  
Functional Theory ◽  
Molecular Electron ◽  
Molecular Electron Density Theory

Conversion of N-trialkylsilyloxy nitronates into bicyclic isoxazoline derivatives has been explored using Density Functional Theory (DFT) method within the context of the Molecular Electron Density Theory (MEDT) at the B97XD(PCM)/6-311G(d,p)...

A DFT study of spherands containing five anisyl groups — Highly preorganized to bind the alkali metal

2006 ◽  
Vol 84 (8) ◽  
pp. 1045-1049 ◽  
Author(s):  
Shabaan AK Elroby ◽  
Kyu Hwan Lee ◽  
Seung Joo Cho ◽  
Alan Hinchliffe
Keyword(s):  
Density Functional Theory ◽  
Binding Energy ◽  
Density Functional ◽  
Ionic Radius ◽  
Binding Energies ◽  
Cavity Size ◽  
X Ray Diffraction ◽  
Functional Theory ◽  
X Ray ◽  
Good Agreement

Although anisyl units are basically poor ligands for metal ions, the rigid placements of their oxygens during synthesis rather than during complexation are undoubtedly responsible for the enhanced binding and selectivity of the spherand. We used standard B3LYP/6-31G** (5d) density functional theory (DFT) to investigate the complexation between spherands containing five anisyl groups, with CH2–O–CH2 (2) and CH2–S–CH2 (3) units in an 18-membered macrocyclic ring, and the cationic guests (Li+, Na+, and K+). Our geometric structure results for spherands 1, 2, and 3 are in good agreement with the previously reported X-ray diffraction data. The absolute values of the binding energy of all the spherands are inversely proportional to the ionic radius of the guests. The results, taken as a whole, show that replacement of one anisyl group by CH2–O–CH2 (2) and CH2–S–CH2 (3) makes the cavity bigger and less preorganized. In addition, both the binding and specificity decrease for small ions. The spherands 2 and 3 appear beautifully preorganized to bind all guests, so it is not surprising that their binding energies are close to the parent spherand 1. Interestingly, there is a clear linear relation between the radius of the cavity and the binding energy (R2 = 0.999).Key words: spherands, preorganization, density functional theory, binding energy, cavity size.

scholarly journals Boron-Decorated Pillared Graphene as the Basic Element for Supercapacitors: An Ab Initio Study

2021 ◽  
Vol 11 (8) ◽  
pp. 3496
Author(s):  
Dmitry A. Kolosov ◽  
Olga E. Glukhova
Keyword(s):  
Density Functional ◽  
Dft Method ◽  
Heat Of Formation ◽  
Basic Element ◽  
Supercapacitor Electrode ◽  
Functional Theory ◽  
Icosahedral Clusters ◽  
New Material ◽  
Principle Density Functional Theory ◽  
Specific Quantum

In this work, using the first-principle density functional theory (DFT) method, we study the properties of a new material based on pillared graphene and the icosahedral clusters of boron B12 as a supercapacitor electrode material. The new composite material demonstrates a high specific quantum capacitance, specific charge density, and a negative value of heat of formation, which indicates its efficiency. It is shown that the density of electronic states increases during the addition of clusters, which predictably leads to an increase in the electrode conductivity. We predict that the use of a composite based on pillared graphene and boron will increase the efficiency of existing supercapacitors.

scholarly journals Changes in CO2 Adsorption Affinity Related to Ni Doping in FeS Surfaces: A DFT-D3 Study

Catalysts ◽  
2021 ◽  
Vol 11 (4) ◽  
pp. 486
Author(s):  
Aleksandar Zivković ◽  
Michiel Somers ◽  
Eloi Camprubi ◽  
Helen E. King ◽  
Mariette Wolthers ◽  
...  
Keyword(s):  
Density Functional ◽  
Organic Molecules ◽  
Ni Doping ◽  
Functional Theory ◽  
Small Organic Molecules ◽  
Adsorption Affinity ◽  
The Origin Of Life ◽  
Carbon Dioxide Co2 ◽  
Partial Desorption ◽  
Good Agreement

Metal sulphides constitute cheap, naturally abundant, and environmentally friendly materials for energy storage applications and chemistry. In particular, iron (II) monosulphide (FeS, mackinawite) is a material of relevance in theories of the origin of life and for heterogenous catalytic applications in the conversion of carbon dioxide (CO2) towards small organic molecules. In natural mackinawite, Fe is often substituted by other metals, however, little is known about how such substitutions alter the chemical activity of the material. Herein, the effect of Ni doping on the structural, electronic, and catalytic properties of FeS surfaces is explored via dispersion-corrected density functional theory simulations. Substitutional Ni dopants, introduced on the Fe site, are readily incorporated into the pristine matrix of FeS, in good agreement with experimental measurements. The CO2 molecule was found to undergo deactivation and partial desorption from the doped surfaces, mainly at the Ni site when compared to undoped FeS surfaces. This behaviour is attributed to the energetically lowered d-band centre position of the doped surface, as a consequence of the increased number of paired electrons originating from the Ni dopant. The reaction and activation energies of CO2 dissociation atop the doped surfaces were found to be increased when compared to pristine surfaces, thus helping to further elucidate the role Ni could have played in the reactivity of FeS. It is expected that Ni doping in other Fe-sulphides may have a similar effect, limiting the catalytic activity of these phases when this dopant is present at their surfaces.

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