scholarly journals Excitons in InP, GaP, and GaxIn1−xP quantum dots: Insights from time-dependent density functional theory

2019 ◽  
Vol 100 (24) ◽  
Author(s):  
Xiaoyu Ma ◽  
Jingjing Min ◽  
Zaiping Zeng ◽  
Christos S. Garoufalis ◽  
Sotirios Baskoutas ◽  
...  
Keyword(s):  
Density Functional Theory ◽  
Quantum Dots ◽  
Density Functional ◽  
Time Dependent ◽  
Functional Theory ◽  
Dependent Density

The optical and electronic properties of graphene quantum dots with oxygen-containing groups: a density functional theory study

2017 ◽  
Vol 5 (24) ◽  
pp. 5984-5993 ◽  
Author(s):  
Jianguang Feng ◽  
Hongzhou Dong ◽  
Liyan Yu ◽  
Lifeng Dong
Keyword(s):  
Density Functional Theory ◽  
Quantum Dots ◽  
Density Functional ◽  
Graphene Quantum Dots ◽  
Time Dependent ◽  
Density Functional Theory Study ◽  
Functional Theory ◽  
Optical And Electronic Properties ◽  
Td Dft ◽  
Dependent Density

The effects of five types of oxygen-containing functional groups (–COOH, –COC–, –OH, –CHO, and –OCH3) on graphene quantum dots (GQDs) are investigated using time-dependent density functional theory (TD-DFT).

scholarly journals Electronic and Optical Properties of Small Hydrogenated Silicon Quantum Dots Using Time-Dependent Density Functional Theory

2015 ◽  
Vol 2015 ◽  
pp. 1-9 ◽  
Author(s):  
Muhammad Mus-’ab Anas ◽  
Geri Gopir
Keyword(s):  
Density Functional Theory ◽  
Quantum Dots ◽  
Absorption Spectrum ◽  
Density Functional ◽  
Time Dependent ◽  
Silicon Quantum Dots ◽  
Functional Theory ◽  
Hydrogenated Silicon ◽  
Small Quantum ◽  
Dependent Density

This paper presents a systematic study of the absorption spectrum of various sizes of small hydrogenated silicon quantum dots of quasi-spherical symmetry using the time-dependent density functional theory (TDDFT). In this study, real-time and real-space implementation of TDDFT involving full propagation of the time-dependent Kohn-Sham equations were used. The experimental results for SiH4and Si5H12showed good agreement with other earlier calculations and experimental data. Then these calculations were extended to study larger hydrogenated silicon quantum dots with diameter up to 1.6 nm. It was found that, for small quantum dots, the absorption spectrum is atomic-like while, for relatively larger (1.6 nm) structure, it shows bulk-like behavior with continuous plateau with noticeable peak. This paper also studied the absorption coefficient of silicon quantum dots as a function of their size. Precisely, the dependence of dot size on the absorption threshold is elucidated. It was found that the silicon quantum dots exhibit direct transition of electron from HOMO to LUMO states; hence this theoretical contribution can be very valuable in discerning the microscopic processes for the future realization of optoelectronic devices.

Benchmark of Simplified Time-Dependent Density Functional Theory for UV-Vis Spectral Properties of Porphyrinoids

2019 ◽  
Author(s):  
Kamal Batra ◽  
Stefan Zahn ◽  
Thomas Heine
Keyword(s):  
Density Functional Theory ◽  
Density Functional ◽  
Large Scale ◽  
Absolute Error ◽  
Time Dependent ◽  
Basis Set ◽  
Basis Sets ◽  
Functional Theory ◽  
Framework Materials ◽  
Dependent Density

<p>We thoroughly benchmark time-dependent density- functional theory for the predictive calculation of UV/Vis spectra of porphyrin derivatives. With the aim to provide an approach that is computationally feasible for large-scale applications such as biological systems or molecular framework materials, albeit performing with high accuracy for the Q-bands, we compare the results given by various computational protocols, including basis sets, density-functionals (including gradient corrected local functionals, hybrids, double hybrids and range-separated functionals), and various variants of time-dependent density-functional theory, including the simplified Tamm-Dancoff approximation. An excellent choice for these calculations is the range-separated functional CAM-B3LYP in combination with the simplified Tamm-Dancoff approximation and a basis set of double-ζ quality def2-SVP (mean absolute error [MAE] of ~0.05 eV). This is not surpassed by more expensive approaches, not even by double hybrid functionals, and solely systematic excitation energy scaling slightly improves the results (MAE ~0.04 eV). </p>

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