scholarly journals Density of Electronic Energy Levels in the Randomly Dilute One-Dimensional Tight-Binding Models

1981 ◽  
Vol 65 (2) ◽  
pp. 751-754 ◽  
Author(s):  
F. Tanaka
Keyword(s):  
Energy Levels ◽  
Tight Binding ◽  
Electronic Energy ◽  
One Dimensional ◽  
Binding Models ◽  
Electronic Energy Levels

Parameter free calculation of the subgap density of states in poly(3-hexylthiophene)

2014 ◽  
Vol 174 ◽  
pp. 255-266 ◽  
Author(s):  
Jarvist M. Frost ◽  
James Kirkpatrick ◽  
Thomas Kirchartz ◽  
Jenny Nelson
Keyword(s):  
Density Of States ◽  
Energy Levels ◽  
Tight Binding ◽  
Electronic Energy ◽  
Film Structure ◽  
Dynamics Simulation ◽  
Characteristic Energy ◽  
Torsional Potential ◽  
Experimental Values ◽  
Electronic Energy Levels

We investigate the influence of intra-chain and inter-chain interactions on the sub-gap density of states in a conjugated polymer using a combination of atomistic molecular dynamics simulation of polymer film structure and tight-binding calculation of electronic energy levels. For disordered assemblies of poly-3-hexylthiophene we find that the tail of the density of hole states is approximately exponential with a characteristic energy of 37 meV, which is similar to experimental values. This tail of states arises mainly from variations in the electronic coupling between neighbouring monomers, and is only slightly influenced by interchain coupling. Thus, knowledge of the disorder in torsion between neighbouring monomers is sufficient to estimate the density of states for the polymer. However, the intrachain torsional disorder is determined largely by the packing of the chains rather than the torsional potential alone. We propose the combination of methods as a tool to design higher mobility conjugated polymers.

scholarly journals Persistent Currents in Continuous One-Dimensional Disordered Rings within the Hartree–Fock Approximation

1997 ◽  
Vol 11 (15) ◽  
pp. 1845-1863 ◽  
Author(s):  
A. Cohen ◽  
R. Berkovits ◽  
A. Heinrich
Keyword(s):  
Energy Levels ◽  
Tight Binding ◽  
Zero Temperature ◽  
Persistent Currents ◽  
One Dimensional ◽  
Hartree Fock ◽  
Self Consistent ◽  
Binding Models ◽  
Interacting Electrons ◽  
Disorder Potential

We present numerical results for the zero temperature persistent currents carried by interacting spinless electrons in disordered one-dimensional continuous rings. The disorder potential is described by a collection of δ-functions at random locations and strengths. The calculations are performed by a self-consistent Hartree–Fock (HF) approximation. Because the HF approximation retains the concept of single-electron levels, we compare the statistics of energy levels of noninteracting electrons with those of interacting electrons as well as of the level persistent currents. We find that the e–e interactions alter the levels and samples persistent currents and introduces a preffered diamagnetic current direction. In contrast to the analogous calculations that recently appeared in the literature for interacting spinless electrons in the presence of moderate disorder in tight-binding models we find no suppression of the persistent currents due to the e–e interactions.

Transferable Tight-Binding Approach Of Si-H Interactions

1997 ◽  
Vol 491 ◽  
Author(s):  
Eunja Kim ◽  
Seung Mi Lee ◽  
Young Hee Lee
Keyword(s):  
Molecular Dynamics ◽  
Potential Energy ◽  
Molecular Dynamics Simulations ◽  
Energy Levels ◽  
Tight Binding ◽  
Electronic Energy ◽  
Binding Parameters ◽  
Exponential Factor ◽  
Dynamics Simulations ◽  
Electronic Energy Levels

ABSTRACTWe construct transferable tight-binding parameters of silicon-hydrogen interactions, reproducing the electronic energy levels and vibrational frequencies of the silane(SiH4) molecule accurately. The potential function was rescaled with the exponential factor in order to ensure that the potential energy is smooth at an appropriate cut-off distance, which is very important in molecular-dynamics simulations. The parameters have been applied to other molecules and various surfaces such as hydrogenated Si(100) surfaces, for example, monohydride, dihydride, and (3×1) phase.

scholarly journals The ultra-violet spectrum of magnesium hydride. 1.—The band at λ 2430

1929 ◽  
Vol 122 (790) ◽  
pp. 442-455 ◽  
Keyword(s):  
Fine Structure ◽  
General Structure ◽  
Energy Levels ◽  
Visible Region ◽  
Ultra Violet ◽  
Present Theory ◽  
Magnesium Hydride ◽  
Electronic Energy ◽  
Band Spectra ◽  
Electronic Energy Levels

The system of bands in the visible region of the emission spectrum of magnesium hydride is now well known. The bands with heads at λλ 5622, 5211, 4845 were first measured by Prof. A. Fowler, who arranged many of the strongest lines in empirical series for identification with absorption lines in the spectra of sun-spots. Later, Heurlinger rearranged these series in the now familiar form of P, Q and R branches, and considered them, with the OH group, as typical of doublet systems in his classification of the fine structure of bands. More recently, W. W. Watson and P. Rudnick have remeasured these bands, using the second order of a 21-foot concave grating, and have carried out a further investigation of the fine structure in the light of the present theory of band spectra. Their detection of an isotope effect of the right order of magnitude, considered with the general structure of the system, and the experimental work on the production of the spectrum, seems conclusive in assigning these bands to the diatomic molecule MgH. The ultra-violet spectrum of magnesium hydride is not so well known. The band at λ 2430 and the series of double lines in the region λ 2940 to λ 3100, which were recorded by Prof. Fowler in 1909 as accompanying the group of bands in the visible region, appear to have undergone no further investigation. In view of the important part played by hydride band spectra in the correlation of molecular and atomic electronic energy levels, it was thought that a study of these features might prove of interest in yielding further information on the energy states of the MgH molecule. The present paper deals with observations on the band at λ 2430; details of an investigation of the other features of the ultra-violet spectrum will be given in a later communication.

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