A boroxol ring doped zigzag boron nitride nanotube: a computational DFT study of the quadrupole coupling constant

2009 ◽  
Vol 87 (6) ◽  
pp. 647-652 ◽  
Author(s):  
Asadollah Boshra ◽  
Ahmad Seif
Keyword(s):  
Density Functional Theory ◽  
Boron Nitride ◽  
Density Functional ◽  
Quadrupole Coupling Constant ◽  
Coupling Constants ◽  
Boron Nitride Nanotube ◽  
Coupling Constant ◽  
Functional Theory ◽  
Quadrupole Coupling ◽  
Dopant Atoms

Based upon density functional theory, we investigate the influence of oxygen dopant atoms that make a boroxol ring on the electrostatic properties of a zigzag (10, 0) boron nitride nanotube in which three of the nitrogen atoms are replaced by oxygen dopant atoms. The electric field gradient (EFG) tensors at the sites of 11B and 14N nuclei were calculated and converted to quadrupole coupling constants (CQ) in the two models of a perfect and a boroxol ring O-doped (10, 0) single-walled boron nitride nanotube (BNNT). Our calculations showed that the CQ values of the boron and nitrogen nuclei along the length of a perfect BNNT are divided into layers. Among the layers the mouth layers have the largest CQ magnitudes. In the doped model, in addition to the mouth layers, the CQ values of those nitrogen nuclei which directly bond to the boroxol ring are increased. However, the CQ values of the boron nuclei that make the boroxol ring and directly bond to the boroxol ring are decreased.

Assessing the Calculation of Exchange Coupling Constants and Spin Crossover Gaps Using the Approximate Projection Model to Improve Density Function Calculations

2019 ◽  
Author(s):  
Xianghai Sheng ◽  
Lee Thompson ◽  
Hrant Hratchian
Keyword(s):  
Density Functional Theory ◽  
Exchange Coupling ◽  
Density Functional ◽  
Spin Crossover ◽  
Coupling Constants ◽  
Spin Projection ◽  
Coupling Constant ◽  
Projection Model ◽  
Functional Theory

This work evaluates the quality of exchange coupling constant and spin crossover gap calculations using density functional theory corrected by the Approximate Projection model. Results show that improvements using the Approximate Projection model range from modest to significant. This study demonstrates that, at least for the class of systems examined here, spin-projection generally improves the quality of density functional theory calculations of J-coupling constants and spin crossover gaps. Furthermore, it is shown that spin-projection can be important for both geometry optimization and energy evaluations. The Approximate Project model provides an affordable and practical approach for effectively correcting spin-contamination errors in molecular exchange coupling constant and spin crossover gap calculations.

DENSITY FUNCTIONAL THEORY STUDY ON THE SINGLE-WALL BORON NITRIDE NANOTUBE, WITH VARIOUS LENGTHS UNDER THE INFLUENCE OF EXTERNAL ELECTRICAL FIELD

2011 ◽  
Vol 10 (04) ◽  
pp. 519-529 ◽  
Author(s):  
DAVOOD FARMANZADEH ◽  
SAMEREH GHAZANFARY
Keyword(s):  
Density Functional Theory ◽  
Boron Nitride ◽  
Density Functional ◽  
Density Functional Theory Calculation ◽  
Atomic Charge ◽  
Boron Nitride Nanotube ◽  
Functional Theory ◽  
Negative Center ◽  
Charge Analysis ◽  
Theory Calculation

Theoretical investigation of the electric responses of the (4,0) zigzag model of single-walled boron nitride nanotube (BNNT) with lengths 10, 12, 14 and 16 Å, has been performed with density functional theory calculation by considering the influence from the external electric field (EF) with strengths 0–1.6 × 10-2 a.u. using B3LYP/6-31G* method. Results show that in both cases, with increase in the length of BNNT and the EF strength, there is a decrease the HOMO-LUMO gap (HLG) values and increase in the electric dipole moment. Natural bond orbital (NBO) atomic charge analysis shows that increasing the EF intensity increases separation of the positive and the negative center of electric charges of BNNT molecule. Results of this study demonstrate that the molecular scale device formed by BNNTs can be significantly influenced by the length of the BNNT itself and the external EF intensity.

scholarly journals Adsorption Properties of Oxygen onH-Capped (5, 5) Boron Nitride Nanotube (BNNT)- A Density Functional Theory

2011 ◽  
Vol 8 (2) ◽  
pp. 609-614 ◽  
Author(s):  
Mohammad T. Baei ◽  
F. Kaveh ◽  
P. Torabi ◽  
S. Zahra Sayyad- Alangi
Keyword(s):  
Density Functional Theory ◽  
Binding Energy ◽  
Boron Nitride ◽  
Density Functional ◽  
Stable State ◽  
Adsorption Properties ◽  
Boron Nitride Nanotube ◽  
Vertical Orientation ◽  
Functional Theory ◽  
The Density Functional Theory

The density functional theory (DFT) has been used to simultaneously investigate physic/chemi-sorption properties of oxygen on the (5, 5) boron nitride nanotube (BNNT). Geometry optimizations were carried out at B3LYP/6-31G*level of theory using gaussian 98 suites of program. physisorption of O2outside the BNNT with a vertical orientation to the tube axis above a boron atom is the most stable state of physisorption and its binding energy is -0.775 kcal/mol. In the chemisorption of O2molecule, the most stable state is above two adjacent B and N atoms of a hexagon with a B-N bond length of 2.503 Å and the binding energy of adsorbed oxygen atoms -14.389 kcal/mol. Based on these results, We also provide the effects of O2adsorption on the electronic properties of BNNTs.

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