Anisotropically Nanostructured Silicon: A First-Principle Approach.

The Difference ◽

ABSTRACTOptical properties of birefringent porous-silicon layers are studied within the density functional theory. Starting from a (110)-oriented supercell of 32 silicon atoms, columns of atoms in directions [100] and [010] are removed and the dangling bonds are saturated with hydrogen atoms. The results show an in-plane anisotropy in the dielectric function and in the refractive index (n). The difference Δn defined as n[110] -n[001] is compared with experimental data and a good agreement is observed. Also, the possibility in determining the morphology of pores by using polarized lights is analyzed.

Theoretical calculations of stability, mechanical and thermodynamic properties of IVA group Willemite-II nitrides

Journal of Theoretical and Computational Chemistry ◽

10.1142/s0219633615500248 ◽

2015 ◽

Vol 14 (04) ◽

pp. 1550024 ◽

Cited By ~ 3

Author(s):

Ying-Chun Ding ◽

Min Chen ◽

Wen-Juan Wu

Keyword(s):

Experimental Data ◽

Thermodynamic Properties ◽

First Principles ◽

Density Functional ◽

Theoretical Calculations ◽

Mechanical Anisotropy ◽

First Principles Calculations ◽

Functional Theory ◽

The structural stability and mechanical and thermodynamic properties of WII- A 3 N 4 ( A=C , Si , Ge and Sn ) are calculated by first-principles calculations based on the density functional theory. The calculated lattice parameters and elastic constants of WII- A 3 N 4 ( A=C , Si , Ge and Sn ) are in good agreement with the experimental data and previously calculated values. WII- A 3 N 4 ( A=C , Si , Ge and Sn ) compounds are also found to be thermodynamically and mechanically stable. The results suggest that hardness of WII- C 3 N 4 is the hardest of these C 3 N 4 polymorphs. The hardness of WII- Sn 3 N 4 is the smallest among WII- A 3 N 4 ( A=C , Si , Ge and Sn ). Furthermore, the mechanical anisotropy, Debye temperature, the minimum thermal conductivity and thermodynamic properties of WII- A 3 N 4 ( A=C , Si , Ge and Sn ) compounds can be investigated.

Effet of edge fluorination and chlorination on structures, stability, electronic and charge transport properties of benzo[o]bistriphenyleno[2,1,12,11-efghi:2',1',12',11'-uvabc]ovalene molecule : DFT study.

10.21203/rs.3.rs-213420/v1 ◽

2021 ◽

Author(s):

Marius Ousmanou Bouba ◽

Fridolin Tchangnwa Nya ◽

Christine Yvette Ngui ◽

Jean Marie Ndjaka

Keyword(s):

Experimental Data ◽

Density Functional ◽

Charge Carriers ◽

Bandgap Energy ◽

Electron Affinities ◽

New Materials ◽

Functional Theory ◽

Theoretical Investigations ◽

Abstract We have investigated the structures, electronic properties, hole and electron mobilities of ﬂuorinated and chlorinated nanographene of benzo[o]bistriphenyleno[2,1,12,11-efghi:2',1',12',11'-uvabc]ovalene (TCHG) molecules, us- ing the density functional theory (DFT) and Markus-Hush charge transfer theory. The calculated geometric parameters and the IR spectrum for chlorinated TCHG are in good agreement with the experimental data. Our theoretical investigations have shown that ﬂuorination and chlorination signiﬁcantly reduce the bandgap energy of TCHG. The obtained adiabatic electron aﬃnities (AEAs) values are 2.76 and 2.93 eV respectively, indicating the air-stable materials. The calculation of charge carriers mobilities in chlorinated dimer shows that the mobility of the electrons is ten times that of the holes, suggesting an n-type behavior. We have shown that the ﬂuorination and chlorination of TCHG are promising pathways for the design of new materials useful in optoelectronics

Investigations of the Optical Properties of LaNi5 and LaNi4.5Sn0.5

Applied Mechanics and Materials ◽

10.4028/www.scientific.net/amm.321-324.495 ◽

2013 ◽

Vol 321-324 ◽

pp. 495-498 ◽

Cited By ~ 1

Author(s):

Dong Chen ◽

Chao Xu

Keyword(s):

Experimental Data ◽

Refractive Index ◽

Optical Properties ◽

Density Functional ◽

Low Frequency ◽

Potential Method ◽

Frequency Region ◽

Functional Theory ◽

Pseudo Potential

The reflectivity, loss function, refractive index, extinction coefficient and dielectric function of the LaNi5and LaNi4.5Sn0.5intermetallic compounds are investigated through the plane-wave pseudo-potential method based on the density functional theory. The effects of Sn impurity are discussed and some interesting features are found in the low frequency region. Some important optical properties such as static dielectric constant and static refractive index are obtained. The equation [n (0)]2=ε1(0)is satisfied according to our calculation, which indicates that our results are correct and reasonable. Nevertheless, the calculated results need to be testified in the future due to the lack of experimental data.

Theoretical Investigation of Energetic Salts with Pentazolate Anion

Molecules ◽

10.3390/molecules25081783 ◽

2020 ◽

Vol 25 (8) ◽

pp. 1783

Author(s):

Hao-Ran Wang ◽

Chong Zhang ◽

Bing-Cheng Hu ◽

Xue-Hai Ju

Keyword(s):

Density Functional ◽

Dft Method ◽

Functional Theory ◽

Calculated Density ◽

Energetic Salts ◽

Vertical Electron Affinity ◽

The Difference ◽

Nitrogen Contents ◽

Experimental Density

Energetic salts based on pentazolate anion (cyclo-N5−) have attracted much attention due to their high nitrogen contents. However, it is an enormous challenge to efficiently screen out an appropriate cation that can match well with cyclo-N5−. The vertical electron affinity (VEA) of the cations and vertical ionization potential (VIP) of the anions for 135 energetic salts and some cyclo-N5− salts were calculated by the density functional theory (DFT). The magnitudes of VEA and VIP, and their matchability were analyzed. The results based on the calculations at the B3LYP/6-311++G(d,p) and B3LYP/aug-cc-pVTZ levels indicate that there is an excellent compatibility between cyclo-N5− and cation when the difference between the VEA of cation and the VIP of cyclo-N5− anion is −2.8 to −1.0 eV. The densities of the salts were predicted by the DFT method. Relationship between the calculated density and the experimental density was established as ρExpt = 1.111ρcal − 0.06067 with a correlation coefficient of 0.905. This regression equation could be in turn used to calibrate the calculated density of the cyclo-N5− energetic salts accurately. This work provides a favorable way to explore the energetic salts with excellent performance based on cyclo-N5−.

Structural and Magnetic Properties of Mn2NiZ (Z = Ga, In, Sn, Sb) Heusler Alloys from Ab Initio Calculations

Solid State Phenomena ◽

10.4028/www.scientific.net/ssp.233-234.229 ◽

2015 ◽

Vol 233-234 ◽

pp. 229-232 ◽

Cited By ~ 4

Author(s):

Vladimir V. Sokolovskiy ◽

Mikhail A. Zagrebin ◽

Y.A. Sokolovskaya ◽

Vasiliy D. Buchelnikov

Keyword(s):

Magnetic Properties ◽

Ab Initio ◽

Density Functional ◽

Heusler Alloys ◽

Martensitic Transition ◽

Functional Theory ◽

Structural And Magnetic Properties ◽

Structure Calculations ◽

The structural and magnetic properties of Mn-based stoichiometric Heusler alloys have investigated by means of ab initio calculations in framework of the density functional theory. First principles electronic structure calculations have shown that Mn2NiZ (Z = Ga, In, Sn, Sb) alloys are ferrimagnets with antiparallel alignment between the Mn atoms. The martensitic transition can be realized in Mn2NiGa and Mn2NiSn alloys with tetragonal ratio of 1.27 and 1.16, respectively. Calculated properties are in a good agreement with available experimental data.

Calculation of electronic structure and mechanical properties of DO3–Fe75-xSi25Nix intermetallic compounds by first principles

International Journal of Modern Physics B ◽

10.1142/s0217979215500873 ◽

2015 ◽

Vol 29 (13) ◽

pp. 1550087

Author(s):

R. Ma ◽

M. P. Wan ◽

J. Huang ◽

Q. Xie

Keyword(s):

Mechanical Properties ◽

Intermetallic Compounds ◽

First Principles ◽

Electronic Structures ◽

Density Functional ◽

Elastic Parameters ◽

Functional Theory ◽

Ni Content ◽

The Difference

Based on the density functional theory (DFT), the plane-wave pseudopotential method was used to investigate the electronic structures and mechanical properties of DO 3– Fe 75-x Si 25 Ni x(x = 0, 3.125, 6.25 and 9.375) intermetallic compounds. The elastic parameters were calculated, and then the bulk modulus, shear modulus and elastic modulus were derived. The paper then focuses on the discussion of ductility and plasticity. The results show that by adding appropriate Ni to Fe 3 Si intermetallic compound can improve the ductility. But the hardness will increase when the Ni content exceeds 6.25%. Analysis of density of states (DOS) and overlap populations indicates that with the difference of the strength of bonding and activity, there were some differences of ductility among different Ni contents. The Fe 71.875 Ni 3.125 Si 25 has the lowest hardness because the covalent bonding (Fe–Si bond and Si–Ni bond) has the minimum covalent electrons.

Theoretical Study of the Electronic Structures of Li-Doped ZnO

Advanced Materials Research ◽

10.4028/www.scientific.net/amr.535-537.214 ◽

2012 ◽

Vol 535-537 ◽

pp. 214-218

Author(s):

Qi Xin Wan ◽

Jia Yi Chen ◽

Zhi Hua Xiong ◽

Dong Mei Li ◽

Bi Lin Shao ◽

...

Keyword(s):

Electronic Structure ◽

Density Functional ◽

Formation Energy ◽

Lattice Distortion ◽

Theoretical Study ◽

Functional Theory ◽

Li Doping ◽

Doped Zno ◽

The first-principles with pseudopotentials method based on the density functional theory was applied to calculate the geometric structure, the formation energy of impurities and the electronic structure of Li-doped ZnO. In the system of Li-doped ZnO, LiZn can not result in lattice distortion. In contrast with that case, LiO and Lii result in lattice distortion after Li doping in ZnO. In Li-doped ZnO, LiO is the most unstable than the other cases. Simultaneously, Lii is more stable than LiZn according to that Lii has smaller formation energy. Furthermore, the electronic structure of Li-doped ZnO indicates that that LiZn behaves as acceptor, while Lii behaves as donor. In conclusion, in Li-doped ZnO, Lii is always in the system to compensate the acceptor. Singly doping Li in ZnO is difficult to gain p-ZnO for the self-compensation. The results are in good agreement with other calculated and experimental results.

First-Principles Calculations of the Structural, Electronic, Optical and Mechanical Properties of CdS, CdSe and CdTe

Advanced Materials Research ◽

10.4028/www.scientific.net/amr.665.302 ◽

2013 ◽

Vol 665 ◽

pp. 302-306 ◽

Cited By ~ 1

Author(s):

Sheetal Sharma ◽

Ajay Singh Verma

Keyword(s):

Experimental Data ◽

Density Functional ◽

Full Potential ◽

Generalized Gradient ◽

Pressure Derivative ◽

Functional Theory ◽

Augmented Plane Wave ◽

Zinc Blende ◽

Optical And Mechanical Properties ◽

The structural, electronic, optical and elastic properties of zinc-blende compounds (CdX, X = S, Se and Te), were studied using full-potential augmented plane wave plus local orbitals method (FP-LAPW+ lo) within density functional theory, using generalized gradient approximation (GGA). Geometrical optimization of the unit cell (lattice constant, bulk modulus and its pressure derivative) is in good agreement with experimental data. Results for band structures, density of states, and elastic constants (C11, C12 and C44) are presented. We also report our results on optical properties like the complex dielectric functions and the refractive index (n) of these compounds. Our results are in reasonable agreement with the available theoretical and experimental data.

First-principle study of materials involved in incommensurate transitions

Zeitschrift für Kristallographie - Crystalline Materials ◽

10.1524/zkri.220.5.511.65064 ◽

2005 ◽

Vol 220 (5/6) ◽

Cited By ~ 5

Author(s):

Razvan Caracas ◽

Xavier Gonze

Keyword(s):

Density Functional Theory ◽

Density Functional ◽

First Principle ◽

Functional Theory ◽

The Density Functional Theory

AbstractWe discuss the applicability of the density functional theory to the study of incommensurate crystals. After a brief introduction to these aperiodic but ordered materials we present several types of

Analysis of vibratinal spectra of 8-hydroxyquinoline and its 5,7-dichloro, 5,7-dibromo, 5,7-diiodo and 5,7-dinitro derivatives based on density functional theory calculations

Open Chemistry ◽

10.2478/s11532-006-0061-x ◽

2007 ◽

Vol 5 (1) ◽

pp. 201-220 ◽

Cited By ~ 12

Author(s):

Khaled Bahgat ◽

Abdel Ragheb

Keyword(s):

Density Functional Theory ◽

Dft Calculations ◽

Density Functional ◽

Density Functional Theory Calculations ◽

Basis Set ◽

Normal Coordinate ◽

Functional Theory ◽

Vibrational Bands ◽

AbstractThe geometry, frequency and intensity of the vibrational bands of 8-hydroxyquinoline and its 5,7-dichloro, 5,7-dibromo, 5,7-diiodo and 5,7-dinitro derivatives were obtained by the density functional theory (DFT) calculations with Becke3-Lee-Parr (B3LYP) functional and 6-31G* basis set. The effects of chloride, bromide, iodide and nitro substituent on the vibrational frequencies of 8-hydroxyquinoline have been investigated. The assignments have been proposed with aid of the results of normal coordinate analysis. The observed and calculated spectra are found to be in good agreement.