Do anionic titanium dioxide nano-clusters reach bulk band gap? A density functional theory study

2010 ◽  
pp. NA-NA ◽  
Author(s):  
Zheng-Wang Qu ◽  
Hui Zhu
Keyword(s):  
Density Functional Theory ◽  
Titanium Dioxide ◽  
Band Gap ◽  
Density Functional ◽  
Density Functional Theory Study ◽  
Functional Theory ◽  
Bulk Band

Density Functional Theory Study on Energy Band Gap of Armchair Silicene Nanoribbons with Periodic Nanoholes

MRS Advances ◽  
2016 ◽  
Vol 1 (22) ◽  
pp. 1613-1618 ◽  
Author(s):  
Sadegh Mehdi Aghaei ◽  
Irene Calizo
Keyword(s):  
Density Functional Theory ◽  
Band Gap ◽  
Energy Band ◽  
Quantum Confinement ◽  
Density Functional ◽  
Quantum Confinement Effect ◽  
Density Functional Theory Study ◽  
Energy Band Gap ◽  
Functional Theory ◽  
Silicene Nanoribbons

ABSTRACTIn this study, density functional theory (DFT) is employed to investigate the electronic properties of armchair silicene nanoribbons perforated with periodic nanoholes (ASiNRPNHs). The dangling bonds of armchair silicene nanoribbons (ASiNR) are passivated by mono- (:H) or di-hydrogen (:2H) atoms. Our results show that the ASiNRs can be categorized into three groups based on their width: W = 3P − 1, 3P, and 3P + 1, P is an integer. The band gap value order changes from “EG (3P − 1) < EG (3P) < EG (3P + 1)” to “EG (3P + 1) < EG (3P − 1) < EG (3P)” when edge hydrogenation varies from mono- to di-hydrogenated. The energy band gap values for ASiNRPNHs depend on the nanoribbons width and the repeat periodicity of the nanoholes. The band gap value of ASiNRPNHs is larger than that of pristine ASiNRs when repeat periodicity is even, while it is smaller than that of pristine ASiNRs when repeat periodicity is odd. In general, the value of energy band gap for ASiNRPNHs:2H is larger than that of ASiNRPNHs:H. So a band gap as large as 0.92 eV is achievable with ASiNRPNHs of width 12 and repeat periodicity of 2. Furthermore, creating periodic nanoholes near the edge of the nanoribbons cause a larger band gap due to a strong quantum confinement effect.

ELECTRONIC PROPERTIES OF HgTe WITHIN DIFFERENT STRUCTURES

2013 ◽  
Vol 27 (18) ◽  
pp. 1350086
Author(s):  
HUXIAN ZHAO ◽  
XIAOSHUANG CHEN ◽  
JIANPING LU ◽  
WEI LU
Keyword(s):  
Density Functional Theory ◽  
High Pressure ◽  
Band Gap ◽  
Local Structure ◽  
Density Functional ◽  
Bond Angle ◽  
Density Functional Theory Study ◽  
Functional Theory ◽  
Role Change ◽  
Bcc Structure

We present the results of a density functional theory study of high-pressure structures of HgTe up to bcc structure, which is the highest-pressure structure that has been fully characterized in experiments in the compounds. We investigated the different structures of HgTe and studied the semimetal → semiconductor → conductor transition in detail. We found, in the mechanism for the semimetal → semiconductor transition, the local structure plays a very important role. Change in local structure leads to the change in hybridization of bonding, sp3 →sp3d2 and led to the change from semiconductor to conductor. In addition, we focused on the special transition of semimetal → semiconductor. The tiny change of bond angle reduces the p–d repulsion interaction in the compound and a band gap is open up, which indicates the semiconductor property.

N-Alkylthienopyrroledione versus benzothiadiazole pulling units in push–pull copolymers used for photovoltaic applications: density functional theory study

2016 ◽  
Vol 18 (2) ◽  
pp. 1017-1024 ◽  
Author(s):  
Jamin Ku ◽  
Yeongrok Gim ◽  
Yves Lansac ◽  
Yun Hee Jang
Keyword(s):  
Density Functional Theory ◽  
Solar Cells ◽  
Band Gap ◽  
Organic Solar Cells ◽  
Density Functional ◽  
Bulk Heterojunction ◽  
Density Functional Theory Study ◽  
Functional Theory ◽  
Low Band Gap ◽  
Photovoltaic Applications

Low-band-gap push–pull copolymers are promising donor materials for bulk heterojunction organic solar cells.

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