Influence of The Local Microstructure on The Macroscopic Properties of Si1–x–yGexCy, Alloys

1997 ◽  
Vol 469 ◽  
Author(s):  
W. Windl ◽  
J. D. Kress ◽  
A. F. Voter ◽  
J. Menéndez ◽  
O. F. Sankey
Keyword(s):  
Lattice Constant ◽  
First Principles ◽  
Density Functional ◽  
Theoretical Study ◽  
Growth Conditions ◽  
Layer By Layer ◽  
First Principles Calculations ◽  
Functional Formalism ◽  
Vegard’S Law ◽  
Dilute Limit

ABSTRACTWe performed a theoretical study of the microscopic arrangement of the C atoms in Si1–x–yGexCy, alloys using the Sankey local-orbital density-functional formalism. Our first-principles calculations show that in the dilute limit, the lattice constant in Si1–yCy, alloys decreases much more (by about 2/3) with concentration than predicted by Vegard's law. We show thatthis result is consistent with Raman and infrared experiments and with previous empiricalcalculations. As the C concentration increases, the interactions between the C atoms become important: Interstitial C becomes more abundant and increases the lattice constant, and the substitutional C atoms array under appropriate growth conditions. The effect of this ordering on the lattice constant is small, but it can be seen in the Raman spectra of layer-by-layer grown samples.

FIRST PRINCIPLES DENSITY FUNCTIONAL INVESTIGATION OF SUPPORTED TUNGSTEN CLUSTER (Wn; n = 1 TO 6) ON ANCHORED GRAPHITE (0001) SURFACE

2013 ◽  
Vol 02 (03n04) ◽  
pp. 1350015
Author(s):  
SONALI BARMAN ◽  
G. P. DAS ◽  
Y. KAWAZOE
Keyword(s):  
First Principles ◽  
Density Functional ◽  
Metal Clusters ◽  
Theoretical Study ◽  
First Principles Calculations ◽  
Novel Technique ◽  
Defect Site ◽  
Positive Ions ◽  
Spin Polarized ◽  
Functional Investigation

Size-selected Wn clusters can be deposited firmly on a graphite (0001) surface using a novel technique, where the positive ions (of the same metal atom species) embedded on the graphite surface by ion implantation, act as anchors. The size selected metal clusters can then soft land on this anchored surface m [Hayakawa et al., 2009]. We have carried out a systematic theoretical study of the adsorption of Wn (n = 1-6) clusters on anchored graphite (0001) surface, using state-of-art spin-polarized density functional approach. In our first-principles calculations, the graphite (0001) surface has been suitably modeled as a slab separated by large vacuum layers. Wn clusters bond on clean graphite (0001) surface with a rather weak Van-der-Waals interaction. However, on the anchored graphite (0001) surface, the Wn clusters get absorbed at the defect site with a much larger adsorption energy. We report here the results of our first-principles investigation of this supported Wn cluster system, along with their reactivity trend as a function of the cluster size (n).

Theoretical Study of Atoms Filled in Carbon Nanotubes

2016 ◽  
Vol 13 (10) ◽  
pp. 6974-6977
Author(s):  
Shuwen Cui ◽  
Weiwei Liu ◽  
Xiaosong Wang
Keyword(s):  
Carbon Nanotubes ◽  
First Principles ◽  
Density Functional ◽  
Theoretical Study ◽  
Local Density ◽  
First Principles Calculations ◽  
Functional Theory ◽  
One Dimensional ◽  
Local Density Functional Theory ◽  
Foreign Materials

The nano-sized quasi-one dimensional hollow cores of carbon nanotubes make it possible for them to be filled with and wetted by foreign materials. With C, S and Se atoms as example, we have studied the filling and wetting of these atoms into carbon nanotubes from local density functional theory in first principles calculations. The results suggest that the effect of nanotube length is negligible when it exceeds 3.6 Å, there is a relation between nanotube diameter and filling and wetting. Our studies would be important implications for the further use of carbon nanotubes.

Adsorption of sodium diclofenac on graphene: a combined experimental and theoretical study

2016 ◽  
Vol 18 (3) ◽  
pp. 1526-1536 ◽  
Author(s):  
I. M. Jauris ◽  
C. F. Matos ◽  
C. Saucier ◽  
E. C. Lima ◽  
A. J. G. Zarbin ◽  
...  
Keyword(s):  
Density Functional Theory ◽  
First Principles ◽  
Density Functional ◽  
Theoretical Study ◽  
First Principles Calculations ◽  
Functional Theory ◽  
Sodium Diclofenac

The interactions of sodium diclofenac drug (s-DCF) with different graphene species were investigated using both first principles calculations based on Density Functional Theory (DFT) and adsorption experiments.

A theoretical study on the intercalation and diffusion of AlF3 in graphite: its application in rechargeable batteries

2021 ◽  
Vol 23 (35) ◽  
pp. 19579-19589
Author(s):  
Sindy J. Rodríguez ◽  
Adriana E. Candia ◽  
Mario C. G. Passeggi ◽  
Eduardo A. Albanesi ◽  
Gustavo D. Ruano
Keyword(s):  
Density Functional Theory ◽  
First Principles ◽  
Density Functional ◽  
Theoretical Study ◽  
Rechargeable Batteries ◽  
Aluminum Fluoride ◽  
First Principles Calculations ◽  
Functional Theory ◽  
And Diffusion

Using first-principles calculations based on density functional theory (DFT), we study the aluminum fluoride (AlF3) intercalation in graphite as a new possibility to use this molecule in rechargeable batteries, and understand its role when used as a component of the solvent.

The n-type and p-type conductivity mechanisms of bulk BiOCl photocatalyst from hybrid density functional theory calculations

2021 ◽  
Author(s):  
Bo Kong ◽  
Tixian Zeng ◽  
Wentao Wang
Keyword(s):  
First Principles ◽  
Density Functional ◽  
Density Functional Theory Calculations ◽  
Growth Conditions ◽  
Hybrid Density Functional Theory ◽  
First Principles Calculations ◽  
Functional Theory ◽  
Type Conductivity ◽  
P Type ◽  
Hybrid Density Functional

Abstract: In this work, the n-type and p-type conductivity mechanisms of bulk BiOCl are systematically investigated using first-principles calculations. Under the O-rich growth conditions, BiOCl presents the intrinsic p-type conductivity,...

STRUCTURAL, ELECTRONIC, THERMODYNAMIC AND THERMAL PROPERTIES OF ZINC-BLENDE InP, InAs AND THEIR InAsx P1-x TERNARY ALLOYS VIA FIRST PRINCIPLES CALCULATIONS

2013 ◽  
Vol 27 (27) ◽  
pp. 1350166 ◽  
Author(s):  
O. NEMIRI ◽  
S. GHEMID ◽  
Z. CHOUAHDA ◽  
H. MERADJI ◽  
F. EL HAJ HASSAN
Keyword(s):  
Thermal Properties ◽  
Bulk Modulus ◽  
Band Gap ◽  
Lattice Constant ◽  
First Principles ◽  
Density Functional ◽  
Experimental Studies ◽  
Ternary Alloys ◽  
Full Potential ◽  
First Principles Calculations

First-principles calculations are performed to study the structural, electronic, thermodynamic and thermal properties of the InP and InAs bulk materials and InAs x P 1-x ternary alloys using the full potential-linearized augmented plane wave method (FP-LAPW) within the density functional theory (DFT). The dependence of the lattice constant, bulk modulus, band gap, Debye temperature, heat capacity and mixing entropy on the composition x was analyzed. The lattice constant for InAs x P 1-x alloys exhibits a marginal deviation from the Vegard's law. A large deviation of the bulk modulus from linear concentration dependence (LCD) was observed for our alloys. We found that the composition dependence of the energy band gap is almost linear by using the mBJ and EV-GGA approximations. The microscopic origins of the gap bowing were explained and detailed by using the approach of Zunger and co-workers. Furthermore, the calculated phase diagram shows a miscibility gap for these alloys with a high critical temperature. Thermal effects on some macroscopic properties of InAs x P 1-x alloys are predicted using the quasi-harmonic Debye model, in which the phononic effects are considered. This is the first quantitative theoretical prediction of the thermal properties of the InAs x P 1-x alloys, and we still expect the confirmation of experimental studies.

scholarly journals First principles calculations of the electronic and dielectric properties of λ-Ta2O5

TecnoLógicas ◽  
2018 ◽  
Vol 21 (43) ◽  
pp. 43-52 ◽  
Author(s):  
Camilo Valencia-Balvín ◽  
Santiago Pérez-Walton ◽  
Jorge M. Osorio-Guillén
Keyword(s):  
Density Functional Theory ◽  
First Principles ◽  
Density Functional ◽  
Theoretical Study ◽  
Wide Bandgap ◽  
First Principles Calculations ◽  
Functional Theory ◽  
Wide Bandgap Semiconductor ◽  
Exchange Correlation ◽  
Good Agreement

Ta2O5 is a wide-bandgap semiconductor that offers interesting applications in microwavecommunications, mainly related to the manufacture of filters and resonators whosesize is inversely proportional to the dielectric constant of the material. For that reason, inthis work we present a theoretical study, based on density functional theory (using PBEsoland hybrid HSE06 exchange-correlation functionals), of the electronic and dielectricproperties of the orthorhombic model -Ta2O5. We found that this model has a direct gap of2.09 and 3.7 eV with PBEsol and HSE06, respectively. Furthermore, the calculated staticdielectric constant, 51, is in good agreement with the reported values of other phases of thissemiconductor.

scholarly journals Electric and Thermoelectric Properties of Cu12Sb4S13 Tetrahedrite with Impurities

2019 ◽  
Author(s):  
Kamyar Ravaji ◽  
Reza Ezzati ◽  
Amir Hosein Mohammadi ◽  
Seyed Amir Abbas
Keyword(s):  
First Principles ◽  
Figure Of Merit ◽  
Density Functional ◽  
Theoretical Study ◽  
Complex Compounds ◽  
First Principles Calculations ◽  
Functional Theory ◽  
The Density Functional Theory ◽  
Electric Structure ◽  
High Figure

The high figure of merit and earth abundance of Cu12Sb4S13 thermoelectric ma- terials have recently attracted many attentions toward these type of complex compounds. Intrinsic low thermal conductivity, as well as tunable electronic transport properties, make them suitable for thermoelectric power generation. In this study, we perform a comparative theoretical study on the substituted compounds, primarily at the Cu site including known tetrahedrite Cu12Sb4S13, by means of first-principles calculations. The density functional theory of electric structure is applied to investigate the result of substitution.

(Ti/Zr,N) codoped hematite for enhancing the photoelectrochemical activity of water splitting

2015 ◽  
Vol 17 (34) ◽  
pp. 22179-22186 ◽  
Author(s):  
Haijun Pan ◽  
Xiangying Meng ◽  
Dongyan Liu ◽  
Song Li ◽  
Gaowu Qin
Keyword(s):  
Density Functional Theory ◽  
Photocatalytic Activity ◽  
Water Splitting ◽  
First Principles ◽  
Density Functional ◽  
Theoretical Study ◽  
First Principles Calculations ◽  
Photoelectrochemical Activity ◽  
Functional Theory

In this theoretical study, first-principles calculations were carried out to explore the photocatalytic activity of cation (Ti or Zr) and anion (N) compensated codoped hematite based on density functional theory (DFT).

Thermodynamic Stability of Hexagonal and Rhombohedral Bn at Cvd Conditions from Van der Waals Corrected First Principles Calculations

2019 ◽  
Author(s):  
Henrik Pedersen ◽  
Björn Alling ◽  
Hans Högberg ◽  
Annop Ektarawong
Keyword(s):  
Thin Films ◽  
Thermodynamic Stability ◽  
First Principles ◽  
Thermal Equilibrium ◽  
Density Functional ◽  
Van Der Waals ◽  
Chemical Vapor ◽  
First Principles Calculations ◽  
Functional Theory ◽  
The Stability

Thin films of boron nitride (BN), particularly the sp<sup>2</sup>-hybridized polytypes hexagonal BN (h-BN) and rhombohedral BN (r-BN) are interesting for several electronic applications given band gaps in the UV. They are typically deposited close to thermal equilibrium by chemical vapor deposition (CVD) at temperatures and pressures in the regions 1400-1800 K and 1000-10000 Pa, respectively. In this letter, we use van der Waals corrected density functional theory and thermodynamic stability calculations to determine the stability of r-BN and compare it to that of h-BN as well as to cubic BN and wurtzitic BN. We find that r-BN is the stable sp<sup>2</sup>-hybridized phase at CVD conditions, while h-BN is metastable. Thus, our calculations suggest that thin films of h-BN must be deposited far from thermal equilibrium.

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