Electronic structure of on- and off-center hydrogenic impurities in quantum dots and quantum nanowires: energies and dipole polarizability

2018 ◽  
Vol 96 (10) ◽  
pp. 1104-1115 ◽  
Author(s):  
R.L.M. Melono ◽  
D. Dobgima ◽  
O. Motapon
Keyword(s):  
Quantum Dots ◽  
Electric Dipole ◽  
Energy Levels ◽  
Model Potential ◽  
Binding Energies ◽  
Dipole Polarizability ◽  
Cavity Radius ◽  
Quantum Size ◽  
Dipole Polarizabilities

The energy levels, ground state binding energies, and electric dipole polarizabilities of hydrogenic impurities in quantum dots and quantum nanowires have been investigated using a non-relativistic B-spline based variational method. Firstly, we have worked on the characterization of those impurities (donor/electron) in quantum dots and quantum nanowires, considering the two cases where the impurity is centered or off-centered in the nanostructure. Secondly, the electric dipole polarizabilities have been computed and their sensitivity with confinement parameters investigated. So the energies, binding energies, and dipole polarizabilities were reported for the centered and the off-centered donor and electron impurities as a function of the cavity radius and the off-center displacement. We found that the polarization of the studied system greatly depends on the model potential form, the off-center displacement, and the cavity radius. In the case of quantum dots and for the parabolic potential, the convergence of the polarizability for large values of the quantum size is shown. For the quantum nanowire case, we have shown that the polarizability is greater in the case of the z axis displacement than that of the transversal one. This leads to the fact that the system is more polarizable when the impurity is moved along the z axis than the transversal one.

scholarly journals A New Piano-Stool Ruthenium(II) P-Cymene-Based Complex: Crystallographic, Hirshfeld Surface, DFT, and Luminescent Studies

Crystals ◽  
2020 ◽  
Vol 11 (1) ◽  
pp. 13
Author(s):  
Mohd. Muddassir ◽  
Abdullah Alarifi ◽  
Mohd. Afzal
Keyword(s):  
Density Functional ◽  
Weak Interactions ◽  
Energy Levels ◽  
Hirshfeld Surface ◽  
Binding Energies ◽  
Orbital Energy ◽  
Aminosalicylic Acid ◽  
Full Characterization

A new complex (Ru(η6-p-cymene)(5-ASA)Cl2) (1) where 5-ASA is 5-aminosalicylic acid has been prepared by reacting the ruthenium arene precursors ((η6-arene)Ru(μ-Cl)Cl)2, with the 5-ASA ligands in a 1:1 ratio. Full characterization of complex 1 was accomplished by elemental analysis, IR, and TGA following the structure obtained from a single-crystal X-ray pattern. The structural analysis revealed that complex 1 shows a “piano-stool” geometry with Ru-C (2.160(5)- 2.208(5)Å), Ru-N (2.159(4) Å) distances, which is similar to equivalents sister complex. Density functional theory (DFT) was used to calculate the significant molecular orbital energy levels, binding energies, bond angles, bond lengths, and spectral data (FTIR, NMR, and UV–VIS) of complex 1, consistent with the experimental results. The IR and UV–VIS spectra of complex 1 were computed using all of the methods and choose the most appropriate way to discuss. Hirshfeld surface analysis was also executed to understand the role of weak interactions such as H⋯H, C⋯H, C-H⋯π, and vdW interactions, which play a significant role in the crystal environment’s stability. Moreover, the luminescence results at room temperature show that complex 1 gives a more intense emission band positioned at 465 nm upon excitation at 330 nm makes it a suitable candidate for the building of photoluminescent material.

Facile one-step sonochemical synthesis of AgCl quantum dots with enhanced photocatalytic activity and its size effects

2020 ◽  
Vol 13 (06) ◽  
pp. 2051036
Author(s):  
Junjie Zhang ◽  
Hujiabudula Maimaitizi ◽  
Tao Zhang ◽  
Yalkunjan Tursun ◽  
Dilinuer Talifu ◽  
...  
Keyword(s):  
Quantum Dots ◽  
Photocatalytic Activity ◽  
Band Gap ◽  
Size Effects ◽  
Ultrasonic Method ◽  
Energy Levels ◽  
Average Diameter ◽  
Light Illumination ◽  
Quantum Size ◽  
One Step

In this work, a facile ultrasonic method for the fabrication of AgCl quantum dots (AgCl QDs) with an average diameter of about 2.5[Formula: see text]nm was reported for the first time. The material was analyzed by various techniques. In addition, effects of material’s size on its photocatalytic activities were studied. Results suggested that the AgCl QDs exhibited excellent photocatalytic activity to degrade Rhodamine B (RhB) and tetracycline (TC) under visible light illumination, and the degradation rate of RhB (TC) had reached up to 96.6% (72.2%) in 20 min, which was higher than that of AgCl nanoparticles (23[Formula: see text]nm) and AgCl nanospheres (114[Formula: see text]nm), respectively. Besides, the band gap of the material was increased when the size of material decreased from 23[Formula: see text]nm to 2.5[Formula: see text]nm. The significantly improved photocatalytic performance and increased band gap of AgCl QDs were mainly related to the quantum size effects of AgCl, which results in the more electron fluctuation in quantized energy levels and the lower recombination of electrons and holes.

ELECTRIC DIPOLE POLARIZABILITIES OF THE TRITON AND LAMBDA HYPERTRITON

2010 ◽  
Vol 19 (02) ◽  
pp. 225-242 ◽  
Author(s):  
V. F. KHARCHENKO ◽  
A. V. KHARCHENKO
Keyword(s):  
Experimental Data ◽  
Wave Function ◽  
Electric Dipole ◽  
Ground State ◽  
Input Data ◽  
Low Energy ◽  
Dipole Polarizability ◽  
Order Of Magnitude ◽  
Three Body ◽  
Dipole Polarizabilities

A rigorous formalism for determining the electric dipole polarizability of a three-hadron bound complex in the case that the system has only one bound (ground) state has been elaborated. On its basis, by applying a model wave function that takes into account specific features of the structure of the three-body nuclei and using the known low-energy experimental data for the p–n, n–d, and Λ–d systems as input data, we have calculated the values of the electric dipole polarizabilities of the triton αE(3 H ) and lambda hypertriton [Formula: see text]. We have obtained for the triton polarizability the value 0.23 fm3. It follows from our study that the polarizability of the lambda hypertriton is close to 3 fm3 exceeding the polarizabilities of the ordinary three-nucleon nuclei by an order of magnitude.

QUANTUM SIZE EFFECTS ON THE ENERGY LEVELS AND FAR-INFRARED SPECTRA: CHANGES FROM QUANTUM DOTS TO QUANTUM RINGS

2007 ◽  
Vol 21 (27) ◽  
pp. 4715-4724
Author(s):  
HUI PAN
Keyword(s):  
Quantum Dots ◽  
Infrared Spectra ◽  
Size Effects ◽  
Energy Levels ◽  
Far Infrared ◽  
Electron Interaction ◽  
Quantum Size Effects ◽  
Quantum Rings ◽  
Quantum Size ◽  
Far Infrared Spectra

The energy levels and far-infrared spectra of two electrons confined in quantum dots and quantum rings under a magnetic field have been investigated. The size and shape effects of quantum rings on the levels and the spectra are clearly revealed. It is found that the spin oscillation of two electrons in a quantum ring with a magnetic field is caused by the Coulomb interaction. The transitions of two-electron far-infrared spectra are clearly shown from quantum dots to quantum rings. The influence of electron–electron interaction on the energy levels and far-infrared spectra has been discussed. The quantum size effects predict a possibility to observe phenomena related to electron-electron interaction in quantum rings.

Electric dipole and quadrupole moment and dipole polarizability of CS, SiO and SiS

2000 ◽  
Vol 98 (8) ◽  
pp. 481-491 ◽  
Author(s):  
George Maroulis, Constantinos Makris, Deme
Keyword(s):  
Quadrupole Moment ◽  
Electric Dipole ◽  
Dipole Polarizability

Highly Fluorescent Au25-xAgx Nanoclusters Protected with Poly(ethylene glycol) - and Zwitterion-Modified Thiolate Ligands

2018 ◽  
Author(s):  
Dinesh Mishra ◽  
Sisi Wang ◽  
Zhicheng Jin ◽  
Eric Lochner ◽  
Hedi Mattoussi
Keyword(s):  
Quantum Yield ◽  
Near Infrared ◽  
Small Diameter ◽  
Binding Energies ◽  
Thiolate Ligands ◽  
Nir Emission ◽  
Thiolate Complexes ◽  
Long Lifetime ◽  
Poly Ethylene

<p>We describe the growth and characterization of highly fluorescing, near-infrared-emitting nanoclusters made of bimetallic Au<sub>25-x</sub>Ag<sub>x</sub> cores, prepared using various monothiol-appended hydrophobic and hydrophilic ligands. The reaction uses well-defined triphenylphosphine-protected Au<sub>11</sub> clusters (as precursors), which are reacted with Ag(I)-thiolate complexes. The prepared nanoclusters are small (diameter < 2nm, as characterized by TEM) with emission peak at 760 nm and long lifetime (~12 µs). The quantum yield measured for these materials was 0.3 - 0.4 depending on the ligand. XPS measurements show the presence of both metal atoms in the core, with measured binding energies that agree with reported values for nanocluster materials. The NIR emission combined with high quantum yield, small size and ease of surface functionalization afforded by the coating, make these materials suitable to implement investigations that address fundamental questions and potentially useful for biological sensing and imaging applications.<br></p>

Full Optical Rotation Tensor at CCSD Level in the Modified Velocity Gauge

2020 ◽  
Author(s):  
Kaihua Zhang ◽  
Ty Balduf ◽  
Marco Caricato
Keyword(s):  
Electric Dipole ◽  
Optical Rotation ◽  
Electric Quadrupole ◽  
Polarizability Tensor ◽  
Dipole Polarizability ◽  
Difficult Case ◽  
Computationally Efficient ◽  
Rotation Tensor ◽  
Approximate Methods ◽  
Velocity Gauge

<div> <div> <p> </p><div> <div> <div> <p>This work presents the first simulations of the full optical rotation (OR) tensor at coupled cluster with single and double excitations (CCSD) level in the modified velocity gauge (MVG) formalism. The CCSD-MVG OR tensor is origin independent, and each tensor element can in principle be related directly to experimental measurements on oriented systems. We compare the CCSD results with those from two density functionals, B3LYP and CAM-B3LYP, on a test set of 22 chiral molecules. The results show that the functionals consistently overestimate the CCSD results for the individual tensor components and for the trace (which is related to the isotropic OR), by 10-20% with CAM-B3LYP and 20-30% with B3LYP. The data show that the contribution of the electric dipole-magnetic dipole polarizability tensor to the OR tensor is on average twice as large as that of the electric dipole-electric quadrupole polarizability tensor. The difficult case of (1S,4S)-(–)-norbornenone also reveals that the evaluation of the former polarizability tensor is more sensitive than the latter. We attribute the better agreement of CAM-B3LYP with CCSD to the ability of this functional to better reproduce electron delocalization compared with B3LYP, consistently with previous reports on isotropic OR. The CCSD-MVG approach allows the computation of reference data of the full OR tensor, which may be used to test more computationally efficient approximate methods that can be employed to study realistic models of optically active materials. </p> </div> </div> </div> </div> </div>

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