Towards the Description of Covalent Bonds in Subsystem Density-Functional Theory

2013 ◽  
pp. 297-322 ◽  
Author(s):  
Christoph R. Jacob ◽  
Lucas Visscher
Keyword(s):  
Density Functional Theory ◽  
Density Functional ◽  
Covalent Bonds ◽  
Functional Theory

The Bioreductive Alkylation of DNA by Kalafungin: A Theoretical Investigation

2012 ◽  
Vol 65 (4) ◽  
pp. 402 ◽  
Author(s):  
Paul A. Hume ◽  
Margaret A. Brimble ◽  
Jóhannes Reynisson
Keyword(s):  
Density Functional Theory ◽  
Theoretical Investigation ◽  
Density Functional ◽  
Covalent Bonds ◽  
Functional Theory ◽  
Electron Reduction

The thermochemical cascades for the bioreductive alkylation of DNA by kalafungin were calculated using density functional theory (DFT). Guanine (G) was used as a model nucleotide. According to the calculations both one- and two-electron reduction of kalafungin is possible in vivo. Furthermore, a clear pathway was found for both mono- and bis-alkylations of G with the former favoured. Alkylation at C-8 position of G is considerably more exothermic than on the N2-exocyclic amine. In the absence of experimentally identified adduct structures of kalafungin, the results presented here support the idea that this compound readily forms covalent bonds with DNA resulting in pro-mutagenic lesions.

First-principles investigation of MoS2 monolayer adsorbed on SiO2 (0001) Surface

2017 ◽  
Vol 31 (25) ◽  
pp. 1750229 ◽  
Author(s):  
Xiangying Su ◽  
Hongling Cui ◽  
Weiwei Ju ◽  
Yongliang Yong ◽  
Xiaohong Li
Keyword(s):  
Density Functional Theory ◽  
Electronic Structure ◽  
Charge Transfer ◽  
First Principles ◽  
Density Functional ◽  
Density Functional Theory Calculations ◽  
Interlayer Spacing ◽  
Covalent Bonds ◽  
Functional Theory ◽  
Mos2 Monolayer

In this paper, the geometric and electronic structure of MoS2 monolayer (ML) adsorbed on SiO2 (0001) surface were studied by using density functional theory calculations. The calculated interfacial binding energy shows that the MoS2/SiO2 hybrid system is stable. MoS2 ML is bound to the SiO2 surface with a big interlayer spacing and no covalent bonds form at the interface. The study of the density of states and the charge transfer indicates that the interaction between MoS2 ML and the SiO2 substrate is very weak. As a result, the electronic properties of MoS2 ML are almost not affected by the SiO2 substrate. This work will be beneficial to the design of MoS2 ML-based devices where a substrate is needed.

Stability, Electronic and Magnetic Properties of Ca3Ru2O7

2011 ◽  
Vol 217-218 ◽  
pp. 924-929
Author(s):  
Jin Hong Xue ◽  
Jing Chao Chen ◽  
Jie Yu ◽  
Jing Feng ◽  
Yong Pan ◽  
...  
Keyword(s):  
Density Functional Theory ◽  
Magnetic Properties ◽  
Cohesive Energy ◽  
Density Functional ◽  
Theoretical Study ◽  
Magnetic Moments ◽  
Covalent Bonds ◽  
Functional Theory ◽  
Electronic And Magnetic Properties ◽  
The Stability

Ca3Ru2O7 is new tpye of thermoelectric materials.A theoretical study is presented for the stability, electronic and magnetic properties of three phases of this new thermoelectric materials in the framework of density functional theory (DFT). The calculated cohesive energy is -7.94eV/unit. AFM2 are less stable than other pahses. Electronic calculations indicate that Ca3Ru2O7 is metallic in nature. The covalent bonds in these structures are due to orbital overlap between p bands of O and d bands of Ru, and DOS at Fermi level are dominated by d bands of Ru. FM phase have obvious magnetic moments.

scholarly journals Investigation on Structural, Relative Stable, and Electronic Properties of Binary AlnLin (n = 2 – 12) Clusters through Density Functional Theory

2019 ◽  
Vol 26 (2) ◽  
pp. 154-160
Author(s):  
Lei SHI ◽  
Zhiqiang ZHOU ◽  
Tao QU ◽  
Dachun LIU ◽  
Xiumin CHEN ◽  
...  
Keyword(s):  
Density Functional Theory ◽  
Electronic Properties ◽  
Density Functional ◽  
Energy Difference ◽  
Second Order ◽  
Covalent Bonds ◽  
Functional Theory ◽  
Fragmentation Energy ◽  
Order Energy ◽  
Homo Lumo

In the present research, the structural, the relative stable, and the electronic properties of AlnLin (n = 2 – 12) clusters were investigated by density functional theory (DFT). By comparing the calculated values of Al2 and Li2 dimers with experimental ones, the reliability of the proposed method was proved. Furthermore, by considering the values of average binding energy (Eb), vertical ionization potential (VIP), vertical electron affinity (VEA), fragmentation energy (△E), second-order energy difference (△2E), HOMO-LUMO (HL) gap, and chemical hardness (η) were calculated. It was found Fragmentation energy, second-order energy difference, VIP, VEA, the chemical stability and HOMO-LUMO gap exhibit odd-even oscillatory behaviours along with cluster size and have extreme values at n = 5 revealed Al5Li5 cluster yielded excellent stability. Those can be well explained by the density of states (DOS) that Li and Al atoms with stronger covalent bonds. Therefore, Al5Li5 cluster can be used as an ideal candidate for calculating Wilson parameters of Al-Li alloys.

Effect of C on Vacancy Migration in α-Iron

2008 ◽  
Vol 139 ◽  
pp. 157-164 ◽  
Author(s):  
Chu Chun Fu ◽  
Estelle Meslin ◽  
Alain Barbu ◽  
F. Willaime ◽  
V. Oison
Keyword(s):  
Density Functional Theory ◽  
Thermodynamic Model ◽  
High Purity ◽  
Diffusion Coefficients ◽  
Density Functional ◽  
Density Functional Theory Calculations ◽  
Vacancy Diffusion ◽  
Covalent Bonds ◽  
Functional Theory ◽  
Limiting Case

Carbon atoms are always present in Fe-based materials, either as impurities even in high purity samples or as an intrinsic constituent in steels. Density Functional Theory calculations have been performed to study the interaction between C atoms and vacancies (V) in α-Fe. We find that the formation of VCn complexes is energetically favourable for n ≤ 3, with VC2 being the most stable one. The energy gain corresponding to the clustering reaction VCn-1 + C → VCn depends mainly on the strength of C-C covalent bonds. The vacancy diffusivity is shown to be significantly modified by the formation of vacancy-carbon complexes, exhibiting non-Arrhenius behaviour. Effective vacancy diffusion coefficients in α-Fe are calculated as a function of temperature and carbon content using a simplified thermodynamic model. The results are discussed in detail in the limiting case of excess of C with respect to vacancies.

First-Principles Study on Structure and Stability of YAP Crystal

2011 ◽  
Vol 399-401 ◽  
pp. 2144-2148
Author(s):  
Qing Gong Song ◽  
Li Wei Liu ◽  
Yan Bo Wang ◽  
Hui Zhao ◽  
Hui Yu Yan ◽  
...  
Keyword(s):  
Density Functional Theory ◽  
First Principles ◽  
Density Functional ◽  
Formation Energy ◽  
Geometry Optimization ◽  
Mulliken Charge ◽  
Covalent Bonds ◽  
Functional Theory ◽  
Atomic Orbitals ◽  
Good Accordance

The geometry optimization, formation energy, Mulliken populations, and density of states of YAP (YAlO3) crystal are studied by using first-principles method based on density functional theory. The optimal lattice parameters of YAP crystal are in good accordance with experimental results reported. The calculated formation energy (-3.73eV) indicates the excellent structural stability of YAP crystal. The obtained Mulliken charge populations of O, Al and Y atoms and their deviations from the formal ones, as well as overlap populations show YAP crystal is a mixed bond material with stronger ionic and weaker covalent bonds, which is attributed to the hybridization of atomic orbitals. The comprehensive effect of various interactions in the system makes YAP crystal more stable.

Doping effects on the geometric and electronic structure of tin clusters

2019 ◽  
Vol 21 (44) ◽  
pp. 24478-24488 ◽  
Author(s):  
Martin Gleditzsch ◽  
Marc Jäger ◽  
Lukáš F. Pašteka ◽  
Armin Shayeghi ◽  
Rolf Schäfer
Keyword(s):  
Density Functional Theory ◽  
Electronic Structure ◽  
Density Functional ◽  
Beam Deflection ◽  
Functional Theory ◽  
Doping Effects ◽  
Depth Analysis ◽  
Trajectory Simulations

In depth analysis of doping effects on the geometric and electronic structure of tin clusters via electric beam deflection, numerical trajectory simulations and density functional theory.

What correlation effects are covered by density functional theory?

2000 ◽  
Vol 98 (20) ◽  
pp. 1639-1658 ◽  
Author(s):  
Yuan He, Jurgen Grafenstein, Elfi Kraka,
Keyword(s):  
Density Functional Theory ◽  
Density Functional ◽  
Correlation Effects ◽  
Functional Theory
Sign in / Sign up

Export Citation Format

Share Document