scholarly journals Ab initio theory of the negatively charged boron vacancy qubit in hexagonal boron nitride

2020 ◽  
Vol 6 (1) ◽  
Author(s):  
Viktor Ivády ◽  
Gergely Barcza ◽  
Gergő Thiering ◽  
Song Li ◽  
Hanen Hamdi ◽  
...  
Keyword(s):  
Boron Nitride ◽  
Ab Initio ◽  
Density Functional ◽  
Hexagonal Boron Nitride ◽  
Energy Levels ◽  
Quantum Bits ◽  
Density Matrix Renormalization ◽  
Ab Initio Theory ◽  
Optically Detected ◽  
Highly Correlated

AbstractHighly correlated orbitals coupled with phonons in two-dimension are identified for paramagnetic and optically active boron vacancy in hexagonal boron nitride by first principles methods which are responsible for recently observed optically detected magnetic resonance signal. Here, we report ab initio analysis of the correlated electronic structure of this center by density matrix renormalization group and Kohn-Sham density functional theory methods. By establishing the nature of the bright and dark states as well as the position of the energy levels, we provide a complete description of the magneto-optical properties and corresponding radiative and non-radiative routes which are responsible for the optical spin polarization and spin dependent luminescence of the defect. Our findings pave the way toward advancing the identification and characterization of room temperature quantum bits in two-dimensional solids.

Tuning Electronic and Structural Properties of Triple Layers of Intercalated Graphene and Hexagonal Boron Nitride: An Ab-initio Study.

2011 ◽  
Vol 1307 ◽  
Author(s):  
Samir S. Coutinho ◽  
David L. Azevedo ◽  
Douglas S. Galvão
Keyword(s):  
Boron Nitride ◽  
Electric Field ◽  
Ab Initio ◽  
Band Gap ◽  
External Electric Field ◽  
Structural Properties ◽  
Density Functional ◽  
Hexagonal Boron Nitride ◽  
Electronic And Structural Properties ◽  
Gap Values

ABSTRACTRecently, several experiments and theoretical studies demonstrated the possibility of tuning or modulating band gap values of nanostructures composed of bi-layer graphene, bi-layer hexagonal boron-nitride (BN) and hetero-layer combinations. These triple layers systems present several possibilities of stacking. In this work we report an ab initio (within the formalism of density functional theory (DFT)) study of structural and electronic properties of some of these stacked configurations. We observe that an applied external electric field can alter the electronic and structural properties of these systems. With the same value of the applied electric field the band gap values can be increased or decreased, depending on the layer stacking sequences. Strong geometrical deformations were observed. These results show that the application of an external electric field perpendicular to the stacked layers can effectively be used to modulate their inter-layer distances and/or their band gap values.

Ab initio study of the structures and hydrogen storage capacity of (H2)nCH4 compound

2015 ◽  
Vol 29 (13) ◽  
pp. 1550062 ◽  
Author(s):  
Minghui Wang ◽  
Xinlu Cheng ◽  
Dahua Ren ◽  
Hong Zhang ◽  
Yongjian Tang
Keyword(s):  
Boron Nitride ◽  
Hydrogen Storage ◽  
Ab Initio ◽  
Density Functional ◽  
Storage Capacity ◽  
Hexagonal Boron Nitride ◽  
Boron Nitride Nanotubes ◽  
Hydrogen Storage Capacity ◽  
Practical Applications ◽  
The Stability

The hydrogen-rich compound ( H 2)n CH 4 (for n = 1, 2, 3, 4) or for short ( H 2)n M is one of the most promising hydrogen storage materials. The ( H 2)4 M molecule is the best hydrogen-rich compound among the ( H 2)n M structures and it can reach the hydrogen storage capacity of 50.2 wt.%. However, the ( H 2)n M always requires a certain pressure to remain stable. In this work, we first investigated the binding energy of the different structures in ( H 2)n M and energy barrier of H 2 rotation under different pressures at ambient temperature, applying ab initio methods based on van der Waals density functional (vdW-DF). It was found that at 0 GPa, the ( H 2)n M is not stable, while at 5.8 GPa, the stability of ( H 2)n M strongly depends on its structure. We further investigate the Raman spectra of ( H 2)n M structures at 5.8 GPa and found the results were consistent with experiments. Excitingly, we found that boron nitride nanotubes (BNNTs) and graphite and hexagonal boron nitride ( h - BN ) can be used to store ( H 2)4 M , which give insights into hydrogen storage practical applications.

scholarly journals Carbon-Based Band Gap Engineering in the h-BN Analytical Modeling

Materials ◽  
2020 ◽  
Vol 13 (5) ◽  
pp. 1026
Author(s):  
Mohammad Taghi Ahmadi ◽  
Ahmad Razmdideh ◽  
Seyed Saeid Rahimian Koloor ◽  
Michal Petrů
Keyword(s):  
Boron Nitride ◽  
Band Gap ◽  
Density Functional ◽  
Hexagonal Boron Nitride ◽  
Tight Binding ◽  
Band Gap Energy ◽  
Specific Structure ◽  
Partial Substitution ◽  
Generalized Gradient ◽  
Complete Replacement

The absence of a band gap in graphene is a hindrance to its application in electronic devices. Alternately, the complete replacement of carbon atoms with B and N atoms in graphene structures led to the formation of hexagonal boron nitride (h-BN) and caused the opening of its gap. Now, an exciting possibility is a partial substitution of C atoms with B and N atoms in the graphene structure, which caused the formation of a boron nitride composite with specified stoichiometry. BC2N nanotubes are more stable than other triple compounds due to the existence of a maximum number of B–N and C–C bonds. This paper focused on the nearest neighbor’s tight-binding method to explore the dispersion relation of BC2N, which has no chemical bond between its carbon atoms. More specifically, the band dispersion of this specific structure and the effects of energy hopping in boron–carbon and nitrogen–carbon atoms on the band gap are studied. Besides, the band structure is achieved from density functional theory (DFT) using the generalized gradient approximations (GGA) approximation method. This calculation shows that this specific structure is semimetal, and the band gap energy is 0.167 ev.

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