scholarly journals A Quantum Chemistry Approach to the Force Fields of the Asymmetrical Thionyl Halides FS(O)Cl, CF3S(O)F and CF3S(O)Cl

2011 ◽  
Vol 66 (5) ◽  
pp. 499-504
Author(s):  
Angelina del C. Coronel ◽  
Myriam E. Gargiulo ◽  
Eduardo L. Varetti ◽  
Lis E. Fernández
Keyword(s):  
Experimental Data ◽  
Density Functional Theory ◽  
Quantum Mechanics ◽  
Density Functional ◽  
Force Fields ◽  
Internal Force ◽  
Vibrational Properties ◽  
Functional Theory ◽  
Definition Of ◽  
Theoretical Results

The vibrational properties of the asymmetrical thionyl halides FS(O)Cl, CF3S(O)F and CF3S(O)Cl were studied by means of density functional theory (DFT) techniques. The available experimental data and assignments for these molecules were compared with the theoretical results and revised. These data were subsequently used in the definition of the corresponding scaled quantum mechanics (SQM) force fields. A set of internal force constants was also calculated from such force fields

Scaled quantum mechanical force fields for trifluoromethyl selenium derivatives. II. The (CF3)2Se and (CF3Se)2 molecules.

2009 ◽  
Vol 87 (3) ◽  
pp. 507-513 ◽  
Author(s):  
L. E. Fernández ◽  
E. L. Varetti
Keyword(s):  
Experimental Data ◽  
Density Functional ◽  
Force Fields ◽  
Internal Force ◽  
Quantum Mechanical ◽  
Vibrational Properties ◽  
Functional Theory ◽  
Selenium Compounds ◽  
Definition Of ◽  
Theoretical Results

Force fields and vibrational properties of bis(trifluoromethyl)selenide, (CF3)2Se, and bis(trifluoromethyl)diselenide, (CF3Se)2, were calculated using density functional theory (DFT) techniques. The previously available experimental data and assignments for these molecules were confirmed by the theoretical results. These data were subsequently used in the definition of the corresponding scaled quantum mechanical (SQM) force fields. The obtained internal force constants are compared with results previously published for related selenium compounds.

scholarly journals A Quantum Chemistry Approach to the Force Fields of the Thionyl and Selenyl Halides, SOX2 and SeOX2

2007 ◽  
Vol 62 (12) ◽  
pp. 1491-1496
Author(s):  
Lis E. Fernández ◽  
Eduardo L. Varetti
Keyword(s):  
Experimental Data ◽  
Quantum Mechanics ◽  
Quantum Chemistry ◽  
Force Fields ◽  
Internal Force ◽  
Vibrational Frequencies ◽  
Force Constants ◽  
Definition Of ◽  
Theoretical Results

Force fields and vibrational frequencies were calculated for the molecules SOX2 and SeOX2, with X = F, Cl, Br, using DFT techniques. The previously available experimental data and assignments for the six molecules were confirmed by the theoretical results. These data were subsequently used in the definition of the corresponding scaled quantum mechanics (SQM) force fields. A comparison of the obtained internal force constants is made with results reported by other authors for the studied species.

Scaled quantum mechanical force fields for trifluoromethyl selenium derivatives. I. The CF3SeCN and CF3SeCH3 molecules

2006 ◽  
Vol 84 (12) ◽  
pp. 1626-1631 ◽  
Author(s):  
L E Fernández ◽  
E L Varetti
Keyword(s):  
Density Functional ◽  
Force Fields ◽  
Chemical Species ◽  
Mechanical Force ◽  
Force Constants ◽  
Quantum Mechanical ◽  
Functional Theory ◽  
Definition Of ◽  
Theoretical Results ◽  
Mechanical Force Fields

Force fields and vibrational properties were calculated for the trifluoromethyl selenium derivatives, CF3SeCN and CF3SeCH3, by means of density functional theory (DFT) techniques. The existing experimental data and assignments for these molecules were confirmed by the theoretical results. These data were subsequently used in the definition of scaled quantum mechanical force fields for such chemical species. The obtained force constants are compared with results previously published for similar compounds.Key words: trifluoromethyl selenium, force constants, structure, DFT calculation.

A DFT study of thymine and its tautomers

2009 ◽  
Vol 87 (2) ◽  
pp. 406-415 ◽  
Author(s):  
Dongsheng Jiao ◽  
Hongyan Wang ◽  
Yanlan Zhang ◽  
Yu Tang
Keyword(s):  
Experimental Data ◽  
Density Functional Theory ◽  
Ionization Potential ◽  
Density Functional ◽  
The Other ◽  
Basis Sets ◽  
Electron Affinities ◽  
Proton Affinities ◽  
Functional Theory ◽  
Theoretical Results

The structures and the relative energies of six possible tautomers of the thymine base have been studied by density functional theory (DFT) using the B3LYP and BP86 functionals. The keto-thymine (T1) is predicted to be the most stable thymine tautomer, which is consistent with the other theoretical results and experimental data. The corresponding thymine cations and anions are studied using the same level of theory with double-ζ plus polarization and diffuse functions (DZP++) basis sets. The ionization potentials (IPs), the electron affinities (EAs), and proton affinities (PAs) for different protonation sites in thymine base are obtained. T1 has the largest ionization potential and the lowest proton affinity among all the considered thymine tautomers.

scholarly journals Theoretical study of the adsorption of benzene on coinage metals

2014 ◽  
Vol 10 ◽  
pp. 1775-1784 ◽  
Author(s):  
Werner Reckien ◽  
Melanie Eggers ◽  
Thomas Bredow
Keyword(s):  
Experimental Data ◽  
Density Functional Theory ◽  
Density Functional ◽  
Theoretical Study ◽  
Dispersion Correction ◽  
Functional Theory ◽  
Coinage Metals ◽  
Adsorption Energies ◽  
Theoretical Results ◽  
Good Agreement

The adsorption of benzene on the M(111), M(100) and M(110) surfaces of the coinage metals copper (M = Cu), silver (M = Ag) and gold (M = Au) is studied on the basis of density functional theory (DFT) calculations with an empirical dispersion correction (D3). Variants of the Perdew–Burke–Ernzerhof functionals (PBE, RPBE and RevPBE) in combination with different versions of the dispersion correction (D3 and D3(BJ)) are compared. PBE-D3, PBE-D3(BJ) and RPBE-D3 give similar results which exhibit a good agreement with experimental data. RevPBE-D3 and RevPBE-D3(BJ) tend to overestimate adsorption energies. The inclusion of three-center terms (PBE-D3(ABC)) leads to a slightly better agreement with the experiment in most cases. Vertical adsorbate–substrate distances are calculated and compared to previous theoretical results. The observed trends for the surfaces and metals are consistent with the calculated adsorption energies.

Theoretical determination of the structures of CaSiO3 perovskites

2006 ◽  
Vol 62 (6) ◽  
pp. 1025-1030 ◽  
Author(s):  
Razvan Caracas ◽  
Renata M. Wentzcovitch
Keyword(s):  
Crystal Structure ◽  
Experimental Data ◽  
Density Functional Theory ◽  
Density Functional ◽  
Theoretical Determination ◽  
Functional Theory ◽  
Starting Point ◽  
Atomic Coordinates ◽  
The Ideal

Density functional theory is used to determine the possible crystal structure of the CaSiO3 perovskites and their evolution under pressure. The ideal cubic perovskite is considered as a starting point for studying several possible lower-symmetry distorted structures. The theoretical lattice parameters and the atomic coordinates for all the structures are determined, and the results are discussed with respect to experimental data.

scholarly journals Compression Behavior and Vibrational Properties of New Energetic Material LLM-105 Analyzed Using the Dispersion-Corrected Density Functional Theory

Molecules ◽  
2021 ◽  
Vol 26 (22) ◽  
pp. 6831
Author(s):  
Tianming Li ◽  
Junyu Fan ◽  
Zhuoran Wang ◽  
Hanhan Qi ◽  
Yan Su ◽  
...  
Keyword(s):  
Density Functional Theory ◽  
High Pressure ◽  
Uniaxial Compression ◽  
Density Functional ◽  
Structural Parameters ◽  
Energetic Material ◽  
Structure Stability ◽  
Vibrational Properties ◽  
Detailed Knowledge ◽  
Functional Theory

The 2,6-diamino-3,5-dinitropyrazine-1-oxide (LLM-105) is a newly energetic material with an excellent performance and low sensitivity and has attracted considerable attention. On the basis of the dispersion-corrected density functional theory (DFT-D), the high-pressure responses of vibrational properties, in conjunction with structural properties, are used to understand its intermolecular interactions and anisotropic properties under hydrostatic and uniaxial compressions. At ambient and pressure conditions, the DFT-D scheme could reasonably describe the structural parameters of LLM-105. The hydrogen bond network, resembling a parallelogram shape, links two adjacent molecules and contributes to the structure stability under hydrostatic compression. The anisotropy of LLM-105 is pronounced, especially for Raman spectra under uniaxial compression. Specifically, the red-shifts of modes are obtained for [100] and [010] compressions, which are caused by the pressure-induced enhance of the strength of the hydrogen bonds. Importantly, coupling modes and discontinuous Raman shifts are observed along [010] and [001] compressions, which are related to the intramolecular vibrational redistribution and possible structural transformations under uniaxial compressions. Overall, the detailed knowledge of the high-pressure responses of LLM-105 is established from the atomistic level. Uniaxial compression responses provide useful insights for realistic shock conditions.

scholarly journals Charge radii of potassium isotopes in the RMF(BCS)* approach

2022 ◽  
Author(s):  
Rong An ◽  
Shisheng Zhang ◽  
Li-Sheng Geng ◽  
Feng-Shou 张丰收 Zhang
Keyword(s):  
Experimental Data ◽  
Density Functional Theory ◽  
Density Functional ◽  
Mean Field ◽  
Field Studies ◽  
Nuclear Density ◽  
Isotopic Chain ◽  
Functional Theory ◽  
Charge Radii ◽  
Nuclear Density Functional Theory

Abstract We apply the recently proposed RMF(BCS)* ansatz to study the charge radii of the potassium isotopic chain up to $^{52}$K. It is shown that the experimental data can be reproduced rather well, qualitatively similar to the Fayans nuclear density functional theory, but with a slightly better description of the odd-even staggerings (OES). Nonetheless, both methods fail for $^{50}$K and to a lesser extent for $^{48,52}$K. It is shown that if these nuclei are deformed with a $\beta_{20}\approx-0.2$, then one can obtain results consistent with experiments for both charge radii and spin-parities. We argue that beyond mean field studies are needed to properly describe the charge radii of these three nuclei, particularly for $^{50}$K.

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