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First-principles calculations of electronic structure of rhodochrosite with impurity

He Guichun, Li Kun, Li Kun, Guo Tengbo, Li Shaoping, Huang Chaojun, Zeng Qinghua

Physicochemical Problems of Mineral Processing

2020

Vol. 56, iss. 1

195--203

The electronic structure of rhodochrosite containing impurity defects is studied by using the first principles density functional theory. The energy band structure, density of states and electronic distribution are calculated for rhodochrosite crystal models with various impurities (e.g., Cu, Ca, Mg, Zn, Fe). This paper discusses the effects of such defects on the electronic structure of rhodochrosite. The calculation results show that the impurity defects have a great impact on the surface electrical properties of rhodochrosite. For example, Ca and Mg impurities reduce the semiconductor width of rhodochrosite. Both Ca and Mg atoms in orbital bonding act as electron donors in which Ca3p and Mg2p orbits provide electrons while O2p orbits receive electrons. Moreover, the more number of valence electrons of Mn is the weaker covalent interaction between Mn and O atoms will be. Meanwhile, decrease of the total energy of rhodochrosite, makes the structure more stable. When Fe, Zn and Cu impurities are contained, the forbidden gap becomes narrower, which improves the conductivity of rhodochrosite. In addition, impurity bands will be formed in the 3d orbits of rhodochrosite as shown in its density of states, and the number of electrons in 3d orbits will increase. This weakens the covalence of O atoms, decreases the population values of O-Mn, increases the bond length, and enhances the ionicity of O-Mn bonds. The impurity of all defects considered in this study have shown an improved conductivity of rhodochrosite, and increased hole concentration of Mn atoms, which will be of great benefit to the adsorption of anionic collectors and enhance the electrochemical properties for rhodochrosite flotation process.

Band electronic structure and dielectric functions of (C3N2H5)2SbF5 crystals

Andriyevsky B., Czapla Z.

Zeszyty Naukowe Wydziału Elektroniki i Informatyki Politechniki Koszalińskiej

2016

Nr 10

51--60

Structural and electronic properties of the ferroelastic crystal (C3N2H5)2SbF5 of the molecular type were studied by ab initio methods in the framework of the density functional theory. Band electronic structure, density of electronic states and dielectric functions in the range of valence electrons excitations of the crystal in the monoclinic phase (space group no. 11) have been obtained using the plane waves, ultrasoft pseudopotentials and van-der-Waals corrections. The electronic values obtained are discussed from the viewpoint of the layer-type crystal structure of (C3N2H5)2SbF5.

Strukturalne i elektronowe właściwości ferroelektrycznego kryształu (C3N2H5)2SbF5 typu molekularnego zostały obliczone w ramach teorii funkcjonału gęstości (DFT) z wykorzystaniem odpowiedniej metody z pierwszych zasad (ab initio). Pasmowa struktura elektronowa, gęstość stanów elektronowych i funkcje dielektryczne w zakresie wzbudzenia elektronów walencyjnych kryształu zostały obliczone dla strukturalnej fazy jednoskośnej (grupa przestrzenna no. 11) z wykorzystaniem płaskich fal, super pseudopotencjałów miękkich i uwzględnienia poprawek na oddziaływania międzyatomowe typu van-der-Waalsa. Otrzymane wielkości elektronowe zostały omówione pod kątem warstwowej struktury krystalicznej (C3N2H5)2SbF5.

Theoretical study of electron transport properties of an organic molecule

Nara J., Geng W. T., Kino H., Kobayashi N., Ohno T.

Materials Science Poland

2005

Vol. 23, No. 2

383--387

Electron transport properties of benzene-(1,4)-dithiolate sandwiched between two gold electrodes were investigated using first-principles calculations. It was found that the peak energies and the peak widths in the transmission spectra are strongly dependent on the contact structures. Furthermore, the contributions of MOs to the transmission coefficients also depend on the contact structures. Especially, only the channel related to HOMO-3, HOMO, and LUMO+1 contributes to the conductance at zero bias. These results suggest that the determination of the contact structure is essential for estimating the properties of molecular devices.