ELECTRONIC STRUCTURE AND OPTICAL PROPERTIES OF CRYSTALLINE C60

1992 ◽  
Vol 06 (06) ◽  
pp. 309-321 ◽  
Author(s):  
W.Y. CHING ◽  
MING-ZHU HUANG ◽  
YONG-NIAN XU ◽  
FANQI GAN
Keyword(s):  
Optical Properties ◽  
Electronic Structure ◽  
First Principles ◽  
Optical Spectrum ◽  
Local Density ◽  
Low Dielectric Constant ◽  
Experimental Measurements ◽  
Absorption Bands ◽  
Low Dielectric ◽  
Good Agreement

The electronic structure and optical properties of crystalline C 60 and their pressure dependence have been studied by first-principles local density calculations. It is shown that fcc C 60 has a low dielectric constant and an optical spectrum rich in structures. The spectrum shows five disconnected absorption bands in the 1.4 to 7.0 eV region with sharp structures in each band that can be attributed to critical point transitions. This is a manifestation of the localized molecular structure coupled with long range crystalline order unique to the C 60 crystal. At a sufficient high pressure, the structures in the optical spectrum start to merge due to the merging of the bands. These results are in good agreement with some recent experimental measurements.

Disordering of MgAl2O4 spinel from first principles

2000 ◽  
Vol 64 (2) ◽  
pp. 311-317 ◽  
Author(s):  
M. C. Warren ◽  
M. T. Dove ◽  
S. A. T. Redfern
Keyword(s):  
Free Energy ◽  
Electronic Structure ◽  
First Principles ◽  
Large Scale ◽  
Experimental Measurements ◽  
Zero Temperature ◽  
Macroscopic Models ◽  
Tetrahedral Sites ◽  
Degree Of Order ◽  
Good Agreement

AbstractAt high temperature, MgAl2O4 spinel is stabilized by disorder of Mg and Al between octahedral and tetrahedral sites. This behaviour has been measured up to 1700 K in recent neutron experiments, but the extrapolation of subsequently fitted thermodynamic models is not reliable. First principles simulation of the electronic structure of such minerals can in principle accurately predict disorder, but would require unfeasibly large computing resources. We have instead parameterized on-site and short-ranged cluster potentials using a small number of electronic structure simulations at zero temperature. These potentials were then used in large-scale statistical simulations at finite temperatures to predict disordering thermodynamics beyond the range of experimental measurements. Within the temperature range of the experiment, good agreement is obtained for the degree of order. The entropy and free energy are calculated and compared to those from macroscopic models.

STRUCTURAL, ELECTRONIC AND OPTICAL PROPERTIES OF THE TETRAGONAL PHASE OFCaSiO3PEROVSKITE UNDER PRESSURE: FIRST-PRINCIPLES CALCULATIONS

2011 ◽  
Vol 25 (01) ◽  
pp. 41-52 ◽  
Author(s):  
ZI-JIANG LIU ◽  
CAI-RONG ZHANG ◽  
XIAO-WEI SUN ◽  
LU WANG ◽  
TING SONG ◽  
...  
Keyword(s):  
Optical Properties ◽  
Pressure Dependence ◽  
First Principles ◽  
Local Density ◽  
Electronic And Optical Properties ◽  
Plane Wave Method ◽  
Direct Band ◽  
Electron Energy Loss ◽  
Calculated Equilibrium ◽  
Good Agreement

First principles studies of structural, elastic, electronic and optical properties of tetragonal CaSiO3perovskite under pressure are reported using the pseudopotential plane wave method within the local density approximation (LDA). The calculated equilibrium lattice is in good agreement with the available experimental data. The elastic constants and their pressure dependence are calculated using the static finite strain technique. A linear pressure dependence of the elastic stiffnesses is found. Band structures show that tetragonal CaSiO3perovskite is a direct band gap material. In order to understand the optical properties of tetragonal CaSiO3perovskite, the dielectric function, absorption coefficient, optical reflectivity, refractive index, extinction coefficient, and electron energy loss are calculated for radiation up to 40 eV. This is the first quantitative theoretical prediction of the elastic, electronic and optical properties of tetragonal CaSiO3perovskite, and it still awaits experimental confirmation.

Electronic Structure and Optical Properties of a Mn-Doped InSe/WSe2 van der Walls Heterostructure: First Principles Calculations

2020 ◽  
Vol 77 (7) ◽  
pp. 587-591
Author(s):  
Rundong Liang ◽  
Xiuwen Zhao ◽  
Guichao Hu ◽  
Weiwei Yue ◽  
Xiaobo Yuan ◽  
...  
Keyword(s):  
Optical Properties ◽  
Electronic Structure ◽  
First Principles ◽  
First Principles Calculations ◽  
Mn Doped

Magnetic Properties of Embedded Rh Clusters in Ni Matrix

1995 ◽  
Vol 384 ◽  
Author(s):  
Zhi-Qiang Li ◽  
Yuichi Hashi ◽  
Jing-Zhi Yu ◽  
Kaoru Ohno ◽  
Yoshiyuki Kawazoe
Keyword(s):  
Magnetic Properties ◽  
Electronic Structure ◽  
First Principles ◽  
Density Functional ◽  
Local Density ◽  
Magnetic Moments ◽  
Functional Formalism ◽  
Rhodium Clusters ◽  
Spin Polarized ◽  
Local Density Functional

ABSTRACTThe electronic structure and magnetic properties of rhodium clusters with sizes of 1 - 43 atoms embedded in the nickel host are studied by the first-principles spin-polarized calculations within the local density functional formalism. Single Rh atom in Ni matrix is found to have magnetic moment of 0.45μB. Rh13 and Rhl 9 clusters in Ni matrix have lower magnetic moments compared with the free ones. The most interesting finding is tha.t Rh43 cluster, which is bulk-like nonmagnetic in vacuum, becomes ferromagnetic when embedded in the nickel host.

First principles study of the structural, electronic and optical properties of crystalline o-phenanthroline

2016 ◽  
Vol 30 (14) ◽  
pp. 1650077 ◽  
Author(s):  
Hajar Nejatipour ◽  
Mehrdad Dadsetani
Keyword(s):  
Optical Properties ◽  
Electronic Structure ◽  
First Principles ◽  
Binding Energies ◽  
Many Body ◽  
Generalized Gradient ◽  
Generalized Gradient Approximation ◽  
Independent Particle ◽  
Excitonic Effects ◽  
Comprehensive Study

In a comprehensive study, structural properties, electronic structure and optical response of crystalline o-phenanthroline were investigated. Our results show that in generalized gradient approximation (GGA) approximation, o-phenanthroline is a direct bandgap semiconductor of 2.60 eV. In the framework of many-body approach, by solving the Bethe–Salpeter equation (BSE), dielectric properties of crystalline o-phenanthroline were studied and compared with phenanthrene. Highly anisotropic components of the imaginary part of the macroscopic dielectric function in o-phenanthroline show four main excitonic features in the bandgap region. In comparison to phenanthrene, these excitons occur at lower energies. Due to smaller bond lengths originated from the polarity nature of bonds in presence of nitrogen atoms, denser packing, and therefore, a weaker screening effect, exciton binding energies in o-phenanthroline were found to be larger than those in phenanthrene. Our results showed that in comparison to the independent-particle picture, excitonic effects highly redistribute the oscillator strength.

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