scholarly journals Linear-scaling density functional simulations of the effect of crystallographic structure on the electronic and optical properties of fullerene solvates

2017 ◽  
Vol 19 (7) ◽  
pp. 5617-5628 ◽  
Author(s):  
Hong-Tao Xue ◽  
Gabriele Boschetto ◽  
Michal Krompiec ◽  
Graham E. Morse ◽  
Fu-Ling Tang ◽  
...  
Keyword(s):  
Optical Properties ◽  
Optical Absorption ◽  
Dft Calculations ◽  
Density Functional ◽  
Large Scale ◽  
Crystallographic Structure ◽  
Linear Scaling ◽  
Optical Absorption Spectra ◽  
Novel Structure ◽  
Structural And Electronic Properties

Large-scale DFT calculations of fullerene solvates including one novel structure probe, the structural and electronic properties and optical absorption spectra.

scholarly journals Parallel Implementation of Large-Scale Linear Scaling Density Functional Theory Calculations With Numerical Atomic Orbitals in HONPAS

2020 ◽  
Vol 8 ◽  
Author(s):  
Zhaolong Luo ◽  
Xinming Qin ◽  
Lingyun Wan ◽  
Wei Hu ◽  
Jinlong Yang
Keyword(s):  
Density Matrix ◽  
Dft Calculations ◽  
Density Functional ◽  
Large Scale ◽  
Parallel Implementation ◽  
Sparse Matrix ◽  
Matrix Multiplication ◽  
Linear Scaling ◽  
Functional Theory ◽  
Atomic Orbitals

Linear-scaling density functional theory (DFT) is an efficient method to describe the electronic structures of molecules, semiconductors, and insulators to avoid the high cubic-scaling cost in conventional DFT calculations. Here, we present a parallel implementation of linear-scaling density matrix trace correcting (TC) purification algorithm to solve the Kohn–Sham (KS) equations with the numerical atomic orbitals in the HONPAS package. Such a linear-scaling density matrix purification algorithm is based on the Kohn's nearsightedness principle, resulting in a sparse Hamiltonian matrix with localized basis sets in the DFT calculations. Therefore, sparse matrix multiplication is the most time-consuming step in the density matrix purification algorithm for linear-scaling DFT calculations. We propose to use the MPI_Allgather function for parallel programming to deal with the sparse matrix multiplication within the compressed sparse row (CSR) format, which can scale up to hundreds of processing cores on modern heterogeneous supercomputers. We demonstrate the computational accuracy and efficiency of this parallel density matrix purification algorithm by performing large-scale DFT calculations on boron nitrogen nanotubes containing tens of thousands of atoms.

Theoretical study on nanostructural modifications of the Si(111) surface

2019 ◽  
Vol 18 (01) ◽  
pp. 1950005
Author(s):  
Yue-Hang Dong ◽  
Xiao-Hui Liu ◽  
Wan-Sheng Su ◽  
Li-Zhen Zhao ◽  
Qing-Jun Zang ◽  
...  
Keyword(s):  
Density Functional Theory ◽  
Optical Properties ◽  
Optical Absorption ◽  
Dft Calculations ◽  
Electronic Structures ◽  
Density Functional ◽  
Theoretical Study ◽  
Surface Modifications ◽  
Thermal Stabilities ◽  
Functional Theory

Modified Si(111) surface with designed nanostructural modifications including grown pits, nanobars and nanoislands as well as deposited hill-, diamond- and cage-like nanoclusters were studied using density-functional theory (DFT) calculations. The thermal stabilities, electronic structures and optical properties of these various nanostructural modifications of the Si(111) surface were calculated and discussed. The results indicate that the optical absorption of the modified Si(111) surface can be enhanced by these surface modifications especially when depositing diamond-like nanoclusters on the surface.

scholarly journals Tuning the optoelectronic properties of hematite with rhodium doping for photoelectrochemical water splitting using density functional theory approach

2021 ◽  
Vol 11 (1) ◽  
Author(s):  
Abdur Rauf ◽  
Muhammad Adil ◽  
Shabeer Ahmad Mian ◽  
Gul Rahman ◽  
Ejaz Ahmed ◽  
...  
Keyword(s):  
Density Functional Theory ◽  
Optical Properties ◽  
Optical Absorption ◽  
Water Splitting ◽  
Density Functional ◽  
Formation Energy ◽  
Visible Region ◽  
Photoelectrochemical Water Splitting ◽  
Theory Approach ◽  
Functional Theory

AbstractHematite (Fe2O3) is one of the best candidates for photoelectrochemical water splitting due to its abundance and suitable bandgap. However, its efficiency is mostly impeded due to the intrinsically low conductivity and poor light absorption. In this study, we targeted this intrinsic behavior to investigate the thermodynamic stability, photoconductivity and optical properties of rhodium doped hematite using density functional theory. The calculated formation energy of pristine and rhodium doped hematite was − 4.47 eV and − 5.34 eV respectively, suggesting that the doped material is thermodynamically more stable. The DFT results established that the bandgap of doped hematite narrowed down to the lower edge (1.61 eV) in the visible region which enhanced the optical absorption and photoconductivity of the material. Moreover, doped hematite has the ability to absorb a broad spectrum (250–800) nm. The enhanced optical absorption boosted the photocurrent and incident photon to current efficiency. The calculated results also showed that the incorporation of rhodium in hematite induced a redshift in optical properties.

scholarly journals Comparative Study on Electronic Structure and Optical Properties of α-Fe2O3, Ag/α-Fe2O3 and S/α-Fe2O3

Metals ◽  
2021 ◽  
Vol 11 (3) ◽  
pp. 424
Author(s):  
Cuihua Zhao ◽  
Baishi Li ◽  
Xi Zhou ◽  
Jianhua Chen ◽  
Hongqun Tang
Keyword(s):  
Optical Properties ◽  
Optical Absorption ◽  
Electronic Structures ◽  
Density Functional ◽  
Peak Strength ◽  
Visible Range ◽  
High Symmetry ◽  
Functional Theory ◽  
Optical Absorption Peak ◽  
Calculation Results

The electronic structures and optical properties of pure, Ag-doped and S-doped α-Fe2O3 were studied using density functional theory (DFT). The calculation results show that the structure of α-Fe2O3 crystal changes after Ag and S doping, which leads to the different points of the high symmetry of Ag-doped and S-doped α-Fe2O3 with that of pure α-Fe2O3 in the energy band, as well as different Brillouin paths. In addition, the band gap of α-Fe2O3 becomes smaller after Ag and S doping, and the optical absorption peak shifts slightly toward the short wavelength, with the increased peak strength of S/α-Fe2O3 and the decreased peak strength of Ag/α-Fe2O3. However, the optical absorption in the visible range is enhanced after Ag and S doping compared with that of pure α-Fe2O3 when the wavelength is greater than 380 nm, and the optical absorption of S-doped α-Fe2O3 is stronger than that of Ag-doped α-Fe2O3.

scholarly journals Электронная структура и спектры оптического поглощения золотых фуллеренов Au-=SUB=-16-=/SUB=- и Au-=SUB=-20-=/SUB=-

2019 ◽  
Vol 61 (6) ◽  
pp. 1204
Author(s):  
Г.И. Миронов
Keyword(s):  
Optical Properties ◽  
Energy Spectrum ◽  
Optical Absorption ◽  
Near Infrared ◽  
Fourier Transforms ◽  
Green Functions ◽  
Optical Absorption Spectra ◽  
New Class ◽  
Infrared Spectral ◽  
Neighboring Site

AbstractThe electronic and optical properties of gold fullerenes are studied in the framework of the Hubbard model. The expressions of the Fourier transforms of anticommutator Green functions have been obtained for gold fullerenes Au_16 and Au_20, the poles of which determine the energy spectrum of the system under consideration. The calculations are performed for the thermodynamic means that characterize jumps of electrons from a nanosystem site to a neighboring site, the correlation functions demonstrating the possibility of existing two d electrons with oppositely oriented spin projections on the same site of the fullerenes consisting of gold atoms. The optical absorption spectra are presented. The optical absorption peaks of ions $${\text{Au}}_{{20}}^{ - }$$ and $${\text{Au}}_{{16}}^{ - }$$ correspond to a near-infrared spectral region, where the light absorption by blood or a soft tissue is vanishingly small; thus, these ions can be used as a new class of contrast improvements and phototherapeutic means for diagnostics and treatment of cancer.

Structural and Electronic Properties of Oxygen Vacancies in Monoclinic HfO2

2007 ◽  
Vol 996 ◽  
Author(s):  
Peter Broqvist ◽  
Alfredo Pasquarello
Keyword(s):  
Oxygen Vacancy ◽  
Optical Absorption ◽  
Total Energy ◽  
Band Gap ◽  
Electronic Properties ◽  
Density Functional ◽  
Oxygen Vacancies ◽  
Structural And Electronic Properties ◽  
Defect Levels ◽  
Hybrid Density Functional

AbstractWe study structural and electronic properties of the oxygen vacancy in monoclinic HfO2 for five different charge states. We use a hybrid density functional to accurately reproduce the experimental band gap. To compare with measured defect levels, we determine total-energy differences appropriate to the considered experiments. Our results show that the oxygen vacancy can consistently account for the defect levels observed in optical absorption, direct electron injection, and trap-assisted conduction experiments.

Sign in / Sign up

Export Citation Format

Share Document