The Local Structure and I-V Characteristics of Chromium Doped Semiconducting Boron Carbide

2011 ◽  
Vol 1307 ◽  
Author(s):  
Jing Liu ◽  
P. A. Dowben ◽  
Guangfu Luo ◽  
Wai-Ning Mei ◽  
Anil Kumar Rajapitamahuni ◽  
...  
Keyword(s):  
Density Functional Theory ◽  
Boron Carbide ◽  
Local Structure ◽  
Density Functional ◽  
Room Temperature ◽  
Magnetic Ordering ◽  
Computational Results ◽  
Functional Theory ◽  
Spin Configuration ◽  
Current Voltage

ABSTRACTThe local spin configuration and band structure of chromium doped boron carbide calculated by density functional theory suggests local magnetic ordering. While the long range dopant position appears random in the boron carbide semiconductor, the local position and initial empirical/computational results suggest the promise of large magneto-resistive effects. The chromium doped boron carbide thin films, fabricated by boron carbide-chromium co-deposition, were studied by current-voltage (I-V) characteristics measurements. The results provide some reason to believe that magneto-resistive effects are indeed present at room temperature.

Twisted Push - Pull Ethylenes

2008 ◽  
Vol 61 (10) ◽  
pp. 805 ◽  
Author(s):  
Rakesh Naduvile Veedu ◽  
Paul V. Bernhardt ◽  
Rainer Koch ◽  
Curt Wentrup
Keyword(s):  
Density Functional Theory ◽  
Density Functional ◽  
Room Temperature ◽  
Dihedral Angles ◽  
Functional Theory ◽  
Activation Barriers ◽  
Rapid Rotation ◽  
X Ray ◽  
X Ray Crystallography ◽  
Calculated Activation

As determined by X-ray crystallography, Meldrum’s acid derivatives 5, 6, and 8 feature dihedral angles around the central C5=C7 double bond of 14–35°, whereas for the anion 9 this angle is 90°. Density functional theory and MP2 calculations are in agreement with the experimental X-ray data for compounds 5–8, but for anion 9 an angle of only ~65° is predicted. It is concluded that a part of the torsion is due to packing forces in the crystal. It is further concluded that these molecules undergo rapid rotation about the central CC bonds at room temperature (calculated activation barriers 5–14 kcal mol–1).

Magnetic properties of cobalt single layer added on graphene: A density functional theory study

2015 ◽  
Vol 29 (02) ◽  
pp. 1450262 ◽  
Author(s):  
M. Afshar ◽  
H. Doosti
Keyword(s):  
Density Functional Theory ◽  
Density Functional ◽  
Single Layer ◽  
Magnetic Ordering ◽  
Polarization Degree ◽  
Generalized Gradient ◽  
Functional Theory ◽  
Half Metallic ◽  
Cobalt Layer ◽  
Ferromagnetic Ordering

In this paper, we have demonstrated magnetic ordering of single cobalt layer added on graphene using relativistic density functional theory at the level of generalized gradient approximation. We have shown that the single Co layer added on graphene show ferromagnetic ordering with perpendicular alignment to the graphene sheet. In the presence of spin-orbit coupling, a spin-polarization degree of about 92% was found for this quasi-two-dimensional magnetic system where it is shown a nearly half-metallic feature.

A density functional theory approach to the magnetic properties of a coupled single-molecule magnet (Mn7)2 complex — An entangled qubit pair candidate

2013 ◽  
Vol 91 (9) ◽  
pp. 866-871 ◽  
Author(s):  
Silvia Gómez-Coca ◽  
Eliseo Ruiz
Keyword(s):  
Density Functional Theory ◽  
Single Molecule ◽  
Exchange Coupling ◽  
Density Functional ◽  
Relative Strength ◽  
Coupling Constants ◽  
Basis Set ◽  
Theory Approach ◽  
Functional Theory ◽  
Spin Configuration

The exchange coupling constants of a Mn14 complex constituted by two weakly coupled Mn7 moieties were calculated using two different density functional theory (DFT) approaches: the Perdew–Burke–Ernzerhof (PBE) functional with a numerical basis set and the hybrid Becke, three-parameter Lee–Yang–Parr (B3LYP) functional employed with a Gaussian basis set. The sign and relative strength of the exchange coupling constants calculated with both methods were consistent; as expected, the values calculated with the PBE functional were slightly overestimated, as corroborated by comparison with the experimental magnetic susceptibility curve. Both methods gave a ground spin configuration of S = 3/2 for the Mn7 moiety, which was weakly antiferromagnetically coupled with the other Mn7 fragment, leading to an S = 0 ground spin configuration for the entire Mn14 complex.

WORK FUNCTION OF BORON CARBIDE: A DFT CALCULATION

2012 ◽  
Vol 19 (04) ◽  
pp. 1250040 ◽  
Author(s):  
CHUNSHAN HE ◽  
ZHIBING LI ◽  
WEILIANG WANG
Keyword(s):  
Density Functional Theory ◽  
Boron Carbide ◽  
Work Function ◽  
Density Functional ◽  
Dft Calculation ◽  
Slab Model ◽  
Functional Theory ◽  
Work Functions

The work functions of (001) and (00-1) surfaces of B4C are investigated with density functional theory and symmetry slab model. These two surfaces are found to be almost nonpolarized and their work functions are 5.15 eV and 5.46 eV, respectively.

A MOLECULAR DIODE BASED ON CONJUGATED CO-OLIGOMERS

2006 ◽  
Vol 05 (04n05) ◽  
pp. 535-540
Author(s):  
PING BAI ◽  
CHEE CHING CHONG ◽  
ER PING LI ◽  
ZHIKUAN CHEN
Keyword(s):  
Density Functional Theory ◽  
Spatial Orientation ◽  
First Principles ◽  
Density Functional ◽  
Infinite System ◽  
Energy Gap ◽  
Functional Theory ◽  
Molecular Diode ◽  
Current Voltage ◽  
P Type

A molecular diode based on a conjugated co-oligomer composed of p-type and n-type segments is investigated using the first principles method. The co-oligomer is connected to Au electrodes to form an Au –oligomer– Au system. The infinite system is dealt with a finite structure confined in a device region and effects from semi-infinite electrodes. Density functional theory and nonequilibrium Green's function are used to describe the device region self-consistently. The current–voltage (I–V) characteristics of the constructed system are calculated and a rectification behavior is observed. The energy gap and the spatial orientation of molecular orbitals, and the transmission functions are calculated to analyze the I–V characteristics of the molecular diode.

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