BPW91 Method Used in Analyzing Electronic Structures and Magnetic Properties of Nin (2-13) Clusters

2014 ◽  
Vol 809-810 ◽  
pp. 406-411 ◽  
Author(s):  
Mei Yan Yu ◽  
Wan Xia Wang ◽  
Shou Gang Chen
Keyword(s):  
Magnetic Moment ◽  
Electronic Structures ◽  
Dft Method ◽  
Basis Set ◽  
Average Binding Energy ◽  
Ionic Potential ◽  
Nickel Clusters ◽  
Nickel Cluster ◽  
Theoretical Results ◽  
Structure Properties

The bond length, average binding energy, magnetic moment per atom and the ionic potential of Nin(2-13) clusters were calculated in detail. The variations of magnetic moment per atom and the ionic potential agree well with experimental data. Theoretical results show that BPW91/Lanl2dz method is the best method and basis set for nickel clusters research, respectively. The ground state configurations and electronic structure properties of Nin(2-13) clusters were investigated using the BPW91/LanL2DZ level of DFT method. Through the molecular orbital, we could explain the paramagnetic and diamagnetic to the influence of the magnetic moment after different nickel cluster molecular hybridization.

A Comprehensive Computational Study on OCH+-Rg (Rg = He, Ne, Ar, Kr, Xe) Complexes

2003 ◽  
Vol 68 (3) ◽  
pp. 489-508 ◽  
Author(s):  
Yinghong Sheng ◽  
Jerzy Leszczynski
Keyword(s):  
Computational Study ◽  
Relativistic Effects ◽  
Dft Method ◽  
Basis Set ◽  
Rare Gas ◽  
Geometrical Parameters ◽  
Minor Effect ◽  
Dissociation Energies ◽  
Equilibrium Geometries

The equilibrium geometries, harmonic vibrational frenquencies, and the dissociation energies of the OCH+-Rg (Rg = He, Ne, Ar, Kr, and Xe) complexes were calculated at the DFT, MP2, MP4, CCSD, and CCSD(T) levels of theory. In the lighter OCH+-Rg (Rg = He, Ne, Ar) rare gas complexes, the DFT and MP4 methods tend to produce longer Rg-H+ distance than the CCSD(T) level value, and the CCSD-calculated Rg-H+ bond lengths are slightly shorter. DFT method is not reliable to study weak interaction in the OCH+-He and OCH+-Ne complexes. A qualitative result can be obtained for OCH+-Ar complex by using the DFT method; however, a higher-level method using a larger basis set is required for the quantitative predictions. For heavier atom (Kr, Xe)-containing complexes, only the CCSD method predicted longer Rg-H+ distance than that obtained at the CCSD(T) level. The DFT method can be applied to obtain the semiquantitative results. The relativistic effects are expected to have minor effect on the geometrical parameters, the H+-C stretching mode, and the dissociation energy. However, the dissociation energies are sensitive to the quality of the basis set. The nature of interaction between the OCH+ ion and Rg atoms was also analyzed in terms of the interaction energy components.

scholarly journals Spin Gapless Semiconductor–Nonmagnetic Semiconductor Transitions in Fe-Doped Ti2CoSi: First-Principle Calculations

2018 ◽  
Vol 8 (11) ◽  
pp. 2200 ◽  
Author(s):  
Yu Feng ◽  
Zhou Cui ◽  
Ming-sheng Wei ◽  
Bo Wu ◽  
Sikander Azam
Keyword(s):  
Magnetic Moment ◽  
Electronic Structures ◽  
Magnetic Moments ◽  
Total Magnetic Moment ◽  
First Principle ◽  
Half Metallic ◽  
Heusler Compound ◽  
First Principle Calculations ◽  
Metallic Ferromagnet

Employing first-principle calculations, we investigated the influence of the impurity, Fe atom, on magnetism and electronic structures of Heusler compound Ti2CoSi, which is a spin gapless semiconductor (SGS). When the impurity, Fe atom, intervened, Ti2CoSi lost its SGS property. As TiA atoms (which locate at (0, 0, 0) site) are completely occupied by Fe, the compound converts to half-metallic ferromagnet (HMF) TiFeCoSi. During this SGS→HMF transition, the total magnetic moment linearly decreases as Fe concentration increases, following the Slate–Pauling rule well. When all Co atoms are substituted by Fe, the compound converts to nonmagnetic semiconductor Fe2TiSi. During this HMF→nonmagnetic semiconductor transition, when Fe concentration y ranges from y = 0.125 to y = 0.625, the magnetic moment of Fe atom is positive and linearly decreases, while those of impurity Fe and TiB (which locate at (0.25, 0.25, 0.25) site) are negative and linearly increase. When the impurity Fe concentration reaches up to y = 1, the magnetic moments of Ti, Fe, and Si return to zero, and the compound is a nonmagnetic semiconductor.

scholarly journals Theoretical Study of the Reaction of Formation of Some Free Phosphines by Stereoselective Hydrophosphination through DFT Method

2018 ◽  
pp. 1-10
Author(s):  
Kouadio Valery Bohoussou ◽  
Anoubilé Bénié ◽  
Mamadou Guy-Richard Koné ◽  
N’guessan Yao Silvère Diki ◽  
Kafoumba Bamba ◽  
...  
Keyword(s):  
Theoretical Study ◽  
Chemical Reactivity ◽  
Dft Method ◽  
Trans Form ◽  
Dft Methods ◽  
Activation Barriers ◽  
Reactivity Descriptors ◽  
Chemical Reactivity Descriptors ◽  
Theoretical Results ◽  
Cis Isomer

In this work the formation of vinylphosphines was studied through the hydrophosphination reaction. The study aims to rationalize the stereoselectivity of these compounds using quantum DFT methods. This theoretical study of chemical reactivity was conducted at B3LYP/6-311 + G (d, p) level. Global chemical reactivity descriptors, stationary point energies and activation barriers were examined to foretell the relative stability of the stereoisomers formed. The various results obtained have revealed that the addition of arylphosphine to dihalogenoacetylene is stereospecific. The Trans form of vinylphosphines is more stable than the Cis form, when the substituent on phosphorus generates less or no π-conjugations. On the other hand, the Cis isomer is predominant when the aryl radical favors more π-conjugations. The theoretical results obtained are in agreement with the experimental results.

scholarly journals Stability and magnetic properties of isomorphous substituted Si7-xMnx+

2018 ◽  
Vol 56 (1) ◽  
pp. 64
Author(s):  
Nguyen Thanh Tung ◽  
Nguyen Thi Mai ◽  
Ngo Tuan Cuong
Keyword(s):  
Density Functional Theory ◽  
Magnetic Properties ◽  
Magnetic Moment ◽  
Density Functional ◽  
Basis Set ◽  
Pentagonal Bipyramid ◽  
Functional Theory ◽  
Electronic Configurations ◽  
Method Of Density Functional ◽  
Optimized Geometries

The optimized geometries, stability, and magnetic properties of cationic clusters Si7+, Si6Mn+, and Si5Mn2+ have been determined by the method of density functional theory using the B3P86/6-311+G(d) functional/basis set. Their electronic configurations have been analyzed to understand the influence of substituting Si atoms by Mn atoms on the structural and magnetic aspects of Si7+. It is shown that the manganese dopant does not alter the structure of the silicon host but significantly changes its stability and magnetism. In particular, while the magnetic moment of Si7+ is 1 mB, Si5Mn2+ exhibits a strong magnetic moment of 9 mB and that of Si6Mn+ takes a relatively high value of 4 mB. Among studied clusters, the pentagonal bipyramid Si5Mn2+ is assigned as the most stable one.

Multiplicity spin, structure, and charge of iron-verdohemeoxygenase complex: A comparison study by the DFT method

2020 ◽  
Vol 24 (10) ◽  
pp. 1208-1214
Author(s):  
Hamideh Tasharofi ◽  
Maryam Daghighi Asli ◽  
Parisa Rajabali Jamaat
Keyword(s):  
Heme Oxygenase ◽  
Density Functional ◽  
Complex Structure ◽  
Three Dimensional ◽  
Dft Method ◽  
Basis Set ◽  
Dimensional Structure ◽  
Central Metal ◽  
Stable States ◽  
And Function

Recently the three-dimensional structure of verdoheme heme oxygenase complex was revealed. However, many parameters of verdoheme heme oxygenase’s complex structure and their role and function on Heme degradation were unknown. In this work the structure of iron verdoheme in complex with heme oxygenase was compared by the density functional theory (DFT)-based B3LYP method using the 6-31G basis set. Many parameters such as charge of verdoheme and iron as central metal, electron distribution, spin multiplicity of the molecule and proximal substituents effects on verdoheme ring stabilization and their arrangement are discussed and compared for twelve different conformations of the molecules to find the most energetically stable states.

Theoretical study of first row transitional metals effects on stabilization of verdoheme analogues

2019 ◽  
Vol 23 (10) ◽  
pp. 1100-1109
Author(s):  
Afsaneh Taghizadeh ◽  
Maryam Daghighi Asli ◽  
Parisa Rajabali Jamaat
Keyword(s):  
Chemical Potential ◽  
Dft Method ◽  
Basis Set ◽  
Orbital Energy ◽  
Central Metal ◽  
Transitional Metals ◽  
Solvent Phase ◽  
Energy Formula ◽  
Homo And Lumo

Heme catabolism is an important physiological process that converts heme to biliverdin in the presence of heme oxygenase which has an essential role in destroying unwanted heme. Verdohemes, the green iron (II) complexes of the 5-oxaporphyrin macrocycle are produced by oxidative destruction of heme. The main goal of this study is clarification of the central metal effect on stabilization of metal 5-oxaporphyrin molecules. To investigate the role of central metal on geometric and electronic properties of five coordinated verdoheme analogues, the first row transitional metals, including Sc, Ti, V, Cr, Mn, Fe, Co, Ni, Cu and Zn, as the central metal of five-coordinated metal 5-oxaporphyrins were systematically calculated without any symmetry constraint by using the B3LYP as DFT method and the 6-31G basis set in gas and solvent phases. According to the results, the stabilization energy of metal 5-oxaporphyrins increases with atomic mass in the solvent phase more than in the gas phase. By reviewing the properties such as the computed frontier orbital energy, HOMO and LUMO gap energy [Formula: see text], hardness [Formula: see text], chemical potential [Formula: see text], softness (s) and electrophilicity [Formula: see text], the pharmaceutical use of this compound can be discussed.

Tests of second-generation and third-generation density functionals for electron affinities of the alkylthio radicals

2014 ◽  
Vol 13 (04) ◽  
pp. 1450030 ◽  
Author(s):  
Aifang Gao ◽  
Aiguo Li
Keyword(s):  
Dft Method ◽  
Absolute Error ◽  
Molecular Structures ◽  
Basis Set ◽  
Density Functionals ◽  
Electron Affinities ◽  
Generalized Gradient ◽  
Experimental Values ◽  
P Type ◽  
Good Agreement

The molecular structures and electron affinities of the R – S / R – S -( R = CH 3, C 2 H 5, n- C 3 H 7, n- C 4 H 9, n- C 5 H 11, i- C 3 H 7, i- C 4 H 9, t- C 4 H 9) species have been studied using 17 pure and hybrid density functionals (five generalized gradient approximation (GGA) methods, six hybrid GGAs, one meta GGA method and five hybrid meta GGAs). The basis set used in this work is of double-ζ plus polarization quality with additional diffuse s- and p-type functions, denoted by DZP++. The geometries are fully optimized with each DFT method and discussed. Harmonic vibrational frequencies are found to be within 3.5% of available experimental values for most functionals. Three different types of the neutral-anion energy separations have been presented. The theoretical electron affinities of alkylthio radicals are in good agreement with the experiment data. The M06 method is very good for the adiabatic electron affinity calculations, and the average absolute error is 0.0439 eV. The HCTH method performs better for EA prediction. The M06-HF, mPWPW91, VSXC and B98 are also reasonable. The most reliable adiabatic electron affinities are predicted to be 1.864 eV ( CH 3 S ), 1.946 eV ( C 2 H 5 S ), 1.959 eV (n- C 3 H 7 S ), 1.970 eV (n- C 4 H 9 S ), 1.982 eV (n- C 5 H 11 S ), 2.053 eV (i- C 3 H 7 S ), 1.991 eV (i- C 4 H 9 S ) and 2.100 eV (t- C 4 H 9 S ) at the M06/DZP++ level of theory, respectively.

STRUCTURES AND PROPERTIES OF F-DOPED BI-SYSTEM SUPERCONDUCTORS

1992 ◽  
Vol 06 (15) ◽  
pp. 943-954 ◽  
Author(s):  
XIAOHUI GAO ◽  
JIE LI ◽  
DE GAO ◽  
GUODONG ZHENG ◽  
SAI GAO
Keyword(s):  
Critical Current ◽  
Potential Barrier ◽  
Flux Pinning ◽  
Hole Concentration ◽  
Superconducting Phase ◽  
Structures And Properties ◽  
Mechanism Of Superconductivity ◽  
Weak Linkage ◽  
Theoretical Results ◽  
Structure Properties

In this paper, the possibility of F entering the superconducting phase, its position and the structure properties of the superconductors, and the mechanism of superconductivity in F-doped Bi-systems are studied based on experimental and theoretical results. It has been found that, because the ΔT c is narrowed and [Formula: see text] raised, the T co of F-doped Bi-system superconductors increases obviously, with the highest T co at 118 K, that F has entered into the superconducting phase, that generally F can reduce the potential barrier of forming high-T c superconducting phase and improve the superconductivity of Bi-systems, but only if there exists certain amount of Pb in the system, and that with F-doping the weak linkage of superconductor is decreased, the flux pinning is enhanced, the carrier-hole concentration is increased, and the critical current is improved.

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