BiVO3 : A Bi-based material with promising uv-visible light absorption properties

Abstract

Spin polarized density functional theory calculations on a predicted BiVO 3 crystal structure is presented. An orthorhombic phase with space group P nma is observed to be highly stable compared to the aristotype cubic structure. An optical band gap of 1.92 eV and a strong optical absorption at 2.25 eV-which lie in the visible region of the solar spectra-are estimated at the coupled-perturbed hybrid density-functional theory level. In addition, the band-structure analysis somewhat shows dispersion at the valence and conduction bands, and the binding energy of the excitons is calculated to be quite low, which can be possibly dissociated at room temperature. BiVO 3 is, therefore, expected to be a promising candidate worth being investigated for visible light driven photocatalytic applications. Simulated infrared and Raman spectra are reported, which could represent a guideline for future experiments, along with a full characterization of structural, electronic, and dynamic properties.

Tellurium Doping and the Structural, Electronic, and Optical Properties of NaYS2(1–x)Te2xAlloys

“…Because the exciton generation is faster than atomic motions in the crystal, only the electron density can reorganize at this time scale giving an unrelaxed exciton. 42 The unrelaxed exciton binding energy can be evaluated only from ε ∞ . After a characteristic time lag due to difference in the characteristic time scales of nuclear and electronic motions, when the nuclei/ions relax to adapt to the altered electron density, a relaxed exciton results.…”

The position operator problem in periodic calculations with an emphasis on theoretical spectroscopy

“…where the sum goes over the N exc excited states, {c k } are the electronic wave functions of the kth excited state, and c 0 is the electronic ground state wave function. In eqn (4), the terms f À and g + are defined in terms of the energy difference between the ground-state and excited state, o k0 , the frequency of incident light, o, and the life-time of the excitation G. 15,18 Electric dipole moment integrals, for non-periodic calculations, and bulk polarization integrals, for periodic calculations, are not only needed for the calculation of the polarizability, [19][20][21][22] but also for the simulation of vibrational and electronic spectra such as IR spectra, 13,23,24 Vibrational Circular Dichroism (VCD) spectra, 25,26 Raman spectra, 17,[27][28][29][30][31][32] and Raman Optical Activity (ROA) spectra, 15,33 sum frequency generation spectra, 34,35 and two-dimensional IR spectroscopy. 36 For the evaluation of properties that are related to the electric dipole moment and to the polarization, a light-matter interaction Hamiltonian is usually applied.…”

“…37 By applying perturbation theory in explicitly kdependent formulations of DFT, the effect of an electric field has been considered for calculations of e.g. polarizabilities and hyperpolarizabilities, [19][20][21][22] IR 13,24 and vibrational Raman spectra, [27][28][29][30][31] and second harmonic generation. 38 Generally, the Berry phase j Berry can be calculated as the line integral of the Berry connection along a closed loop in reciprocal space as…”

“…In eqn (4), the terms f − and g + are defined in terms of the energy difference between the ground-state and excited state, ω k 0 , the frequency of incident light, ω , and the life-time of the excitation Γ . 15,18 Electric dipole moment integrals, for non-periodic calculations, and bulk polarization integrals, for periodic calculations, are not only needed for the calculation of the polarizability, 19–22 but also for the simulation of vibrational and electronic spectra such as IR spectra, 13,23,24 Vibrational Circular Dichroism (VCD) spectra, 25,26 Raman spectra, 17,27–32 and Raman Optical Activity (ROA) spectra, 15,33 sum frequency generation spectra, 34,35 and two-dimensional IR spectroscopy. 36…”