Boron Segregation on the ${\rm Si}(111)\sqrt{3} \times \sqrt{3}{\rm R}30^\circ$ Surface

In this paper we report the results of calculations of the energies associated with the segregation of boron on the [Formula: see text] surface. These calculations have been carried out using the plane wave pseudopotential density functional code fhi98md in a periodic slab formalism. The segregation energy is predicted to be -0.77 eV. This prediction is intermediate between the "experimentally determined" values of -0.33 eV and -0.48 eV, and the values of -1.83 eV and -2.10 eV determined from AM1 cluster calculations. Additional information has been obtained by performing ab initio density functional cluster calculations using the Gaussian98 code. These latter results indicate that the AM1 calculations significantly overestimate the segregation energy of boron on the [Formula: see text] surface. They also provide strong support for the fhi98md calculations.

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Atomic-Orbital and Plane-Wave Approaches to Ferromagnetic Properties of NixFe1-x Nanowires

MRS Advances ◽

10.1557/adv.2017.159 ◽

2017 ◽

Vol 2 (9) ◽

pp. 507-512

Author(s):

Ikram Ziti ◽

M. R. Britel ◽

Chumin Wang

Keyword(s):

Plane Wave ◽

Ab Initio ◽

Density Functional ◽

Atomic Orbital ◽

Magnetic Moments ◽

Geometry Optimization ◽

Magnetic Sensors ◽

Magnetic Nanowires ◽

Electronic Density ◽

Periodic Arrays

ABSTRACTThere are growing interests on magnetic nanowires, due to their potential applications in magnetic sensors and recording devices. In this work, we report a comparative ab-initio study based on the Density Functional Theory (DFT) of NixFe1-x nanowire periodic arrays by using atomic-orbital and plane-wave basis respectively through DMol3 and CASTEP codes. After performing the geometry optimization, we calculate the spin-polarized electronic density of states, average interatomic distance, and magnetic moments. For pure Ni nanowires (x = 1, the dependence of the magnetic moment obtained from CASTEP calculations on the cutoff energy, as well as that from DMol3 on the thermal smearing parameter is analyzed in detail. Both ab-initio calculations predict close magnetic moments for each x, being slightly larger those of DMol3 obtained with significantly less computing cost. Finally, these DFT results are compared with experimental data and a good agreement is observed.

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Asymmetrically distorted structures of monosilacyclobutane and disilacyclobutane radical cations studied by ab initio and density functional theories

Canadian Journal of Chemistry ◽

10.1139/v2012-035 ◽

2012 ◽

Vol 90 (7) ◽

pp. 584-596

Author(s):

Z.J. Cai ◽

Y.J. Shi

Keyword(s):

Ab Initio ◽

Potential Energy Surfaces ◽

Density Functional ◽

Strong Support ◽

Electronic States ◽

Radical Cations ◽

Ring Structure ◽

The Other ◽

Significant Difference ◽

Ring Structures

The geometrical and electronic structures of a series of six monosilacyclobutane and 1,3-disilacyclobutane radical cations were systematically studied using ab initio and density functional theories. It was shown that all six radical cations possess an asymmetrically distorted structure in their ground electronic states. In the asymmetrically distorted C1 structure of monosilacyclobutane cations, one Si–C bond was elongated and the other was shortened. For the disilacyclobutane cations, two ring bonds were elongated and the other two contracted. The asymmetrical distortion was enhanced by exocyclic methyl substitutions and weakened by endocyclic Si substitution. The unpaired electron was localized mainly in the elongated σ(Si–C) ring bond(s) in all six cations. Studies of the excited electronic states of the cations provided strong support that the asymmetrical distortion in the four-membered-ring cations originates from the second-order Jahn–Teller effect. It was found that the puckered ring structures in the monosilacyclobutane molecules were maintained upon ionization, whereas 1,3-disilacyclobutane cations changed to a planar ring structure. Examination of the potential energy surfaces of all six cations showed that the Si–C ring bond elongation is the main contributor to the significant difference in the geometry change between monosilacyclobutane and disilacyclobutane species upon ionization.

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FIRST PRINCIPLES STUDY OF BORON SEGREGATION ON THE ${\rm Si}(111)(\sqrt{3} \times \sqrt{3}){\rm R}30^{\circ}$ SURFACE

Surface Review and Letters ◽

10.1142/s0218625x09012470 ◽

2009 ◽

Vol 16 (02) ◽

pp. 167-170 ◽

Cited By ~ 2

Author(s):

V. G. ZAVODINSKY ◽

E. N. CHUKUROV ◽

I. A. KUYANOV

Keyword(s):

Plane Wave ◽

First Principles ◽

Local Density Approximation ◽

Local Density ◽

Experimental Studies ◽

Basis Set ◽

Published Data ◽

Density Approximation ◽

Segregation Energy ◽

Boron Segregation

Segregation of boron on [Formula: see text] surface has been studied using the periodical calculations within the local density approximation. The obtained segregation energy (enthalpy) of about -1.9 eV is close to the published data of experimental studies and previous cluster semiempirical calculations. The influence of plane-wave basis set cutoff energy and the slab unit cell depth on the value of segregation energy has been investigated.

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Structural stability, elastic constants, bonding characteristics and thermal properties of zincblende, rocksalt and fluorite phases in copper nitrides: plane-wave pseudo-potential ab initio calculations

Open Physics ◽

10.2478/s11534-010-0063-3 ◽

2011 ◽

Vol 9 (1) ◽

Cited By ~ 9

Author(s):

Nawel Kanoun-Bouayed ◽

Mohammed Kanoun ◽

Souraya Goumri-Said

Keyword(s):

Plane Wave ◽

Ab Initio Calculations ◽

Ab Initio ◽

Elastic Constants ◽

Density Functional ◽

Structural Parameters ◽

Population Analysis ◽

Mulliken Charge ◽

Bonding Properties ◽

Pseudo Potential

AbstractWe report plane-wave pseudo-potential ab initio calculations using density functional theory in order to investigate the structural parameters, elastic constants, bonding properties and polycrystalline parameters of copper nitrides in zincblende, rocksalt and fluorite structures. Total and partial densities of states indicate a metallic character of these copper nitrides. We estimate bond strengths and types of atomic bonds using Mulliken charge density population analysis and by calculating the electronic localized function. These results reveal the coexistence of covalent, ionic, and metallic bonding.

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