scholarly journals QUESTDB : A database of highly accurate excitation energies for the electronic structure community

2021 ◽  
Author(s):  
Mickaël Véril ◽  
Anthony Scemama ◽  
Michel Caffarel ◽  
Filippo Lipparini ◽  
Martial Boggio‐Pasqua ◽  
...  
Keyword(s):  
Electronic Structure ◽  
Excitation Energies ◽  
Structure Community

Can boron form coordination complexes with diffuse electrons? Evidence for linked solvated electron precursors

2022 ◽  
Author(s):  
Zachary Jordan ◽  
Shahriar N. Khan ◽  
Benjamin A. Jackson ◽  
Evangelos Miliordos
Keyword(s):  
Electronic Structure ◽  
Density Functional ◽  
Molecular System ◽  
Hydrocarbon Chain ◽  
Solvated Electron ◽  
Excitation Energies ◽  
Functional Theory ◽  
Boron Complexes ◽  
The Stability ◽  
First Time

Abstract Density functional theory and ab initio multi-reference calculations are performed to examine the stability and electronic structure of boron complexes that host diffuse electrons in their periphery. Such complexes (solvated electron precursors or SEPs) have been experimentally identified and studied theoretically for several s- and d-block metals. For the first time, we demonstrate that a p-block metalloid element can form a stable SEP when appropriate ligands are chosen. We show that three ammonia and one methyl ligands can displace two of the three boron valence electrons to a peripheral 1s-type orbital. The shell model for these outer electrons is identical to previous SEP systems (1s, 1p, 1d, 2s). Further, we preformed the first examination of a molecular system consisting of two SEPs bridged by a hydrocarbon chain. The electronic structure of these dimers is very similar to that of traditional diatomic molecules forming bonding and anti-bonding σ and π orbitals. Their ground state electronic structure resembles that of two He atoms, and our results indicate that the excitation energies are nearly independent of the chain length for four carbon atoms or longer. These findings pave the way for the development of novel materials similar to expanded metals and electrides.

ChemInform Abstract: C60 and Its Ions: Electronic Structure, Ionization Potentials, and Excitation Energies

ChemInform ◽  
2010 ◽  
Vol 23 (7) ◽  
pp. no-no
Author(s):  
A. H. H. CHANG ◽  
W. C. ERMLER ◽  
R. M. PITZER
Keyword(s):  
Electronic Structure ◽  
Ionization Potentials ◽  
Excitation Energies

scholarly journals Machine Learning for Absorption Cross Sections

2020 ◽  
Author(s):  
Bao-Xin Xue ◽  
Mario Barbatti ◽  
Pavlo O. Dral
Keyword(s):  
Machine Learning ◽  
Electronic Structure ◽  
Electronic Properties ◽  
Cross Sections ◽  
Ridge Regression ◽  
Computational Cost ◽  
Oscillator Strengths ◽  
Absorption Cross ◽  
Statistical Sampling ◽  
Excitation Energies

We present a machine learning (ML) method to accelerate the nuclear ensemble approach (NEA) for computing absorption cross sections. ML-NEA is used to calculate cross sections on vast ensembles of nuclear geometries to reduce the error due to insufficient statistical sampling. The electronic properties — excitation energies and oscillator strengths — are calculated with a reference electronic structure method only for relatively few points in the ensemble. Kernel-ridge-regression-based ML combined with the RE descriptor as implemented in MLatom is used to predict these properties for the remaining tens of thousands of points in the ensemble without incurring much of additional computational cost. We demonstrate for two examples, benzene and a 9-dicyanomethylene derivative of acridine, that ML-NEA can produce statistically converged cross sections even for very challenging cases and even with as few as several hundreds of training points.

EMISSION BAND SPECTRA OF NITROGEN: A STUDY OF SOME SINGLET SYSTEMS

1957 ◽  
Vol 35 (2) ◽  
pp. 216-234 ◽  
Author(s):  
Alf Lofthus
Keyword(s):  
Electronic Structure ◽  
High Resolution ◽  
Emission Band ◽  
Rotational Structure ◽  
Electron Configuration ◽  
Excitation Energies ◽  
Local Perturbations ◽  
Singlet States ◽  
Band Spectra ◽  
Vibrational Constants

Ten bands of Gaydon's and Herman's singlet systems and eight new bands have been photographed under high resolution and analyzed in detail. Two of the new transitions were shown to be [Formula: see text], the upper state being in one case identical with Watson's and Koontz's state g, and one new transition to be 1Δg—ω1Δu in type. It is proposed that the new state 1Δg has the same electron configuration as the [Formula: see text] state. Two bands in the red and one band in the ultraviolet could not be assigned with certainty. Local perturbations in the [Formula: see text] state were observed and shown to be caused by the ν = 1 level of the [Formula: see text] state. Observed pecularities in the rotational structure of most of the upper states are proposed to be indicative of a transition from case b′ to d′ coupling. In some cases pronounced decreases in branch intensities were observed, indicating predissociations probably caused by "forbidden" intercombination processes. Identification of the electronic structure of the higher singlet states in terms of Rydberg orbitals is discussed. Rotational and vibrational constants and excitation energies are presented.

scholarly journals Electronic Structure and Surface Properties of Copper Thiocyanate: A Promising Hole Transport Material for Organic Photovoltaic Cells

Materials ◽  
2020 ◽  
Vol 13 (24) ◽  
pp. 5765
Author(s):  
Bonaventure A. Odeke ◽  
Gyang D. Chung ◽  
Jesutofunmi A. Fajemisin ◽  
Kabir S. Suraj ◽  
Denis K. Tonui ◽  
...  
Keyword(s):  
Electronic Structure ◽  
Solar Cells ◽  
Dimethyl Sulfoxide ◽  
Valence Band ◽  
Surface Properties ◽  
Density Functional ◽  
Power Conversion ◽  
Hole Transport ◽  
Excitation Energies ◽  
X Ray

Considering the significance of hexagonal copper thiocyanate (β-CuSCN) in several optoelectronic technologies and applications, it is essential to investigate its electronic structure and surface properties. Herein, we have employed density functional theory (DFT) calculations to characterise the band structure, density of states, and the energy-dependent X-ray photoelectron (XPS) valence band spectra at variable excitation energies of β-CuSCN. The surface properties in the absence and presence of dimethyl sulfoxide (DMSO), a solvent additive for improving perovskite solar cells’ power conversion efficiency, have also been systematically characterised. β-CuSCN is shown to be an indirect band gap material (Eg = 3.68 eV) with the valence band edge demonstrated to change from being dominated by Cu-3d at soft X-ray ionisation photon energies to Cu-3p at hard X-ray ionisation photon energies. The adsorption energy of dimethyl sulfoxide (DMSO) on the (100) and (110) β-CuSCN surfaces is calculated at −1.12 and −0.91 eV, respectively. The presence of DMSO on the surface is shown to have a stabilisation effect, lowering the surface energy and tuning the work function of the β-CuSCN surfaces, which is desirable for organic solar cells to achieve high power conversion efficiencies.

EL2 and the Electronic Structure of the AsGa—Asi Pair in GaAs: the Role of Jahn-Teller Relaxation

1987 ◽  
Vol 104 ◽  
Author(s):  
G. A. Baraff ◽  
M. Lannoo ◽  
M. Schluter
Keyword(s):  
Electronic Structure ◽  
Energy Functional ◽  
Excitation Energies ◽  
Defect Pair ◽  
Weakly Interacting ◽  
Jahn Teller

ABSTRACTThe levels and excitation energies of the weakly interacting AsGa—Asi defect pair have been calculated using the model energy functional introduced by Baraff and Schluter, modified so as to allow Jahn Teller relaxation to distort the Asi away from the symmetry site. The physics underlying this calculation and the results emerging from it are described in this paper. We find that many previously unrelated experimental observations about EL2 are well accounted for by this model. However, there are still some controversial aspects of the fit of the model to the observed properties of EL2 which we cite as requiring further study.

Ground and excited states analysis of alkali metal ethylenediamine and crown ether complexes

2021 ◽  
Author(s):  
Isuru R. Ariyarathna ◽  
Evangelos Miliordos
Keyword(s):  
Electronic Structure ◽  
Crown Ether ◽  
Excited States ◽  
Electronic Structure Calculations ◽  
Excitation Energies ◽  
Crown Ether Complexes ◽  
High Level ◽  
Structure Calculations ◽  
Sodium And Potassium ◽  
Optimized Geometries

High-level electronic structure calculations are carried out to obtain optimized geometries and excitation energies of neutral lithium, sodium, and potassium complexes with two ethylenediamine and one or two crown ether...

Sign in / Sign up

Export Citation Format

Share Document