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Ab initio full potential calculations on the mineral sulfides sphalerite, pyrite and chalcopyrite
2002 (English)Independent thesis Advanced level (professional degree), 20 credits / 30 HE creditsStudent thesis
Abstract [en]

The number of possible applications for sulfide minerals is increasing. Sulfide minerals are not only the main source for the production of different metals, but also of interest for the semiconductor industry. There is an overall need for better understanding of the sulfide mineral properties, especially surfaces. This master thesis presents the bulk electronic structure of sphalerite, pyrite and chalcopyrite. An \textit{ab initio} full potential linear combination of atomic orbitals density functional approach, that uses the local density approximation, is used to perform the calculation. The exchange term is approximated with the Dirac exchange functional, and the Vosko-Wilk-Nusair parameterization of the Cepler-Alder free electron gas is used for correlation. Gaussian type functions are used as basis functions. The sphalerite band gap is calculated to be direct with a width of 2.23 eV. The sphalerite valence band is 5.2 eV wide and composed of a mixture of S and Zn orbitals. The band below the valence band located around -6.2 eV is mainly composed of Zn 3d orbitals. The sulfur 3s orbitals give rise to a band located around -12.3 eV. Pyrite is calculated to be a semiconductor with an indirect band gap of 0.51 eV, and a direct gap of 0.55 eV. The valence band is 1.25 eV wide and mainly composed of nonbonding Fe 3d orbitals. The band below the valence band are a mixture of Fe and S orbitals, it is 4.9 eV wide. The sulfur 3s orbitals in pyrite are split into a bonding and antibonding range, due to the short interatomic distance between the sulfur dumbbells. Chalcopyrite is calculated to be a conductor, with no bands crossing at the Fermi level. The bands origin from the sulfur 3s orbitals located at -13.2 eV are quite similar to the sulfur 3s band in sphalerite, though somewhat shifted to lower energy. The top of the valence band consists of a mixture of orbitals from all atoms, the lower part has metal character.

Place, publisher, year, edition, pages
2002.
Keyword [en]
Technology, sphalerite, pyrite, chalcopyrite
Keyword [sv]
Teknik
Identifiers
URN: urn:nbn:se:ltu:diva-58218ISRN: LTU-EX--02/238--SELocal ID: ecf1a78e-d158-423c-a656-a1979b8911b3OAI: oai:DiVA.org:ltu-58218DiVA: diva2:1031606
Subject / course
Student thesis, at least 30 credits
Educational program
Engineering Physics, master's level
Examiners
Note
Validerat; 20101217 (root)Available from: 2016-10-04 Created: 2016-10-04Bibliographically approved

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