Tight-binding model of selenium disordered phases

Molina, D.; Lomba, Enrique; Kahl, Gerhard

doi:10.1103/physrevb.60.6372

Cited by 29 publications

(22 citation statements)

References 26 publications

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“…In Ref. 4 it became clear that the independent electron approximation inherent to the TB model is responsible for an excess of charge transfer between threefold coordinated and terminal atoms-close to 0.9e Ϫ . As a consequence, an excess of threefold and onefold coordinated atoms was observed-most of them forming valence alternation pairs, VAP's-in marked disagreement with the ab initio reference results 6 and the experimental evidence.…”

Section: Introductionmentioning

confidence: 99%

Hubbard corrections in a tight-binding Hamiltonian for Se: Effects on the band structure, local order, and dynamics

2000

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A recently proposed tight-binding Hamiltonian model for Selenium ͓Phys. Rev. B 60, 6372 ͑1999͔͒ is modified to incorporate the effect of charge-charge correlations via an empirical Hubbard contribution. The correction term is fitted to reproduce the cohesive energy curve of a finite chain structure while retaining the quality of the tight-binding fit for various rings, infinite chains, and solid phases. The Hubbard corrections are incorporated in the Hellman-Feynman forces via a first-order perturbation theory. The structure and dynamics of various thermodynamics states, obtained from molecular-dynamic simulations in the canonical ensemble, evidence a marked decrease in the number of threefold and onefold defects in the Se chains as a result of the charge-transfer minimization. This translates into a better agreement with ab initio simulation data and experimental evidence, which also reflects in improved estimates for the bond angle distribution functions and the electronic band structure. On the other hand, the pair distribution function and the atomic structure factor are hardly affected by the Hubbard corrections. The minimization of charge transfer brings about the stabilization of longer chains and consequently the microscopic dynamics is also affected, showing both a decrease of the diffusion coefficients and an increase of the bond-stretching band in the vibrational spectrum.

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Section: Introductionmentioning

confidence: 99%

Hubbard corrections in a tight-binding Hamiltonian for Se: Effects on the band structure, local order, and dynamics

2000

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“…The TB parametrization [9] has been introduced for disordered selenium following the techniques developed by Goodwin et al [11]. It was thoroughly tested by molecular dynamics calculations in liquid and amorphous phases and the results were compared to experiments and to ab initio calculations.…”

Section: Simulation Methodsmentioning

confidence: 99%

Photo-induced volume changes in selenium. Tight-binding molecular dynamics study

Hegedüs¹,

Koháry²,

Kugler³

et al. 2004

Journal of Non-Crystalline Solids

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Tight-binding molecular dynamics simulations of photo-excitations in small Se clusters (isolated Se 8 ring and helical Se chain) and glassy Se networks (containing 162 atoms) were carried out in order to analyze the photo-induced instability in amorphous selenium. In the cluster systems after taking an electron from the highest occupied molecular orbital to the lowest unoccupied molecular orbital a bond breaking occurs. In the glassy networks photo-induced volume expansion was observed and at the same time the number of coordination defects changed significantly due to illumination.

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“…Self-consistency was taken into account via the on-site Hubbard term within the TB model [13,14]. We used the velocity Verlet algorithm to follow the motion of atoms with a time step equal to Dt ¼ 2 fs.…”

Section: Sample Preparationmentioning

confidence: 99%