Scaling of energy gaps in phosphorene nanoflakes

2021 ◽  
Author(s):  
Linan Huang ◽  
Jun Zhong ◽  
Weidong Sheng ◽  
Aiping Zhou
Keyword(s):  
Experimental Result ◽  
Effective Dielectric Constant ◽  
Exponential Dependence ◽  
Electron Hole ◽  
Sio2 Substrate ◽  
Hartree Fock ◽  
Optical Gap ◽  
Energy Gaps ◽  
Hole Interaction ◽  
Scaling Rule

Abstract Electronic structure of phosphorene nanoflakes which consist of hundreds of phosphorus atoms are studied in the framework of unrestricted Hartree-Fock approach. On the base of Pariser-Parr-Pople model for electron-electron interactions, a simplified Bethe-Salpeter formalism is established for the calculation of excitation states of the system. Taking into account the electron-hole interaction in various dielectric environments, the optical gap of a triangular phosphorene nanoflake is shown to increase as the screening effect becomes stronger while its graphene counterpart exhibits just the opposite dependence. After confirming an exponential dependence of the optical gap on the effective dielectric constant, the quasiparticle and optical gaps are also found to obey an exponential scaling rule against the total number of atoms in the nanoflakes, respectively. By extrapolating the dependence on the size of the system, one is able to estimate the exciton binding energy of a monolayer phosphorene sheet on a SiO2 substrate to be 0.894 eV. The result is found to agree well with the previous experimental result of $ 0.9 eV.

scholarly journals Optical response and band structure of LiCoO2 including electron-hole interaction effects

2021 ◽  
Vol 104 (11) ◽  
Author(s):  
Santosh Kumar Radha ◽  
Walter R. L. Lambrecht ◽  
Brian Cunningham ◽  
Myrta Grüning ◽  
Dimitar Pashov ◽  
...  
Keyword(s):  
Band Structure ◽  
Optical Response ◽  
Interaction Effects ◽  
Electron Hole ◽  
Hole Interaction

scholarly journals Static Quadrupole Moment of the First Excited State of 28Si

1980 ◽  
Vol 33 (3) ◽  
pp. 509 ◽  
Author(s):  
RH Spear ◽  
MP Fewell
Keyword(s):  
Excited State ◽  
Quadrupole Moment ◽  
Coulomb Excitation ◽  
Mean Value ◽  
Experimental Result ◽  
Hartree Fock ◽  
Good Account ◽  
First Excited State ◽  
The Mean ◽  
Static Quadrupole

The reorientation effect in Coulomb excitation has been used to measure the static quadrupole moment Q2+ and B(E2;0+->2+) for the 1�779 MeV first excited state of 28Si. The results obtained are Q2+ = +15�5�3�4 efm2 and B(E2;0+->2+) = 326�20 e2fm4 ? The value obtained for Q2+ confirms the results of other recent determinations using the reorientation effect, and the B(E2; 0+ -> 2 +) value is in excellent agreement with the mean value deduced from previous lifetime determinations. Shell model and Hartree-Fock calculations of Q2+ both give a good account of the experimental result.

The structures and stabilities of singlet and triplet dithiatriazines: a computational study

1988 ◽  
Vol 66 (9) ◽  
pp. 2279-2284 ◽  
Author(s):  
R. E. Hoffmeyer ◽  
W.-T. Chan ◽  
J. D. Goddard ◽  
R. T. Oakley
Keyword(s):  
Excited States ◽  
Electron Correlation ◽  
Computational Study ◽  
Geometry Optimization ◽  
Hartree Fock ◽  
Structural Distortions ◽  
Energy Gaps ◽  
Jahn Teller ◽  
Moller Plesset ◽  
Triplet Excited States

Ab initio molecular orbital and Møller–Plesset perturbation theory calculations have been carried out on two model dithiatriazines RCN3S2 (R = H, NH2). With geometry optimization and the inclusion of electron correlation both of these dithiatriazines are predicted to be ground state singlets. Both molecules have low-lying triplet excited states, with energy gaps of 6.6 (R = H) and 13.0 (R = NH2) kcal mol−1. The singlet dithiatriazines distort from high (C2v) to low (Cs) symmetry, and these changes are important in determining the relative energies of the singlet and triplet molecules. The structural distortions experienced by these molecules are related to Hartree–Fock and Jahn–Teller instabilities in other thiazene heterocycles.

NOVEL ELECTRON GAS SYSTEMS

1999 ◽  
Vol 13 (05n06) ◽  
pp. 479-488 ◽  
Author(s):  
GAETANO SENATORE ◽  
F. RAPISARDA ◽  
S. CONTI
Keyword(s):  
Phase Diagram ◽  
Quantum Wells ◽  
Recent Progress ◽  
Electron Gas ◽  
Total Charge ◽  
Diffusion Monte Carlo ◽  
Electron Hole ◽  
Coupled Quantum Wells ◽  
Hartree Fock ◽  
The Ideal

We review recent progress on the physics of electrons in the bilayered electron gas, relevant to coupled quantum wells in GaAs/AlGaAs heterostructures. First, we focus on the phase diagram of a symmetric bilayer at T=B=0, obtained by diffusion Monte Carlo simulations. It is found that inter–layer correlations stabilize crystalline structures at intermediate inter–layer separation, while favouring a liquid phase at smaller distance. Also, the available DMC evidence is in contrast with the recently (Hartree–Fock) predicted total charge transfer (TCT), whereby all the electron spontaneously jump in one layer. In fact, one can show that such a TCT state is never stable in the ideal bilayer with no tunneling. We finally comment on ongoing DMC investigations on the electron-hole bilayer, where excitonic condensation is expected to take place.

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