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

A recently proposed tight-binding Hamiltonian model for Selenium [Phys. Rev . B 60, 6372 (1999)] is modified to incorporate the effect of charge-charge correlations via an entpirical Hubbard contribution. The correction term i s fitted to reproduce the cohesive energy curve of a finite chain structure while retaining the quality of the tight-binding fit for various rings, in finite chains, and solid phases. The Hubbard corrections are incorporated i n the Hellman-Feynman forces via a first-order perturbation theory. The str ucture and dynamics of various thermodynamics states. obtained from molecul ar-dynamic simulations in the canonical ensemble, evidence a marked decreas e in the number of threefold and onefold defects in the Se chains as a resu lt of the charge-transfer minimization. This translates into a better agree ment with ab initio simulation data and experimental evidence, which also r eflects in improved estimates fur the bond angle distribution functions and the electronic band structure. On the other hand, the pair distribution fu nction and the atomic structure factor are hardly affected by the Hubbard c orrections. The minimization of charge transfer brings about the stabilizat ion of longer chains and consequently the microscopic dynamics is also affe cted, showing both a decrease of the diffusion coefficients and an increase of the bond-stretching band in the vibrational spectrum.