Lattice dynamics of trigonal selenium. I. Phonon spectra

Teuchert, W.D.; Geick, R.; Landwehr, G.; Wendel, H.; Weber, W.

doi:10.1088/0022-3719/8/22/013

Cited by 27 publications

(11 citation statements)

References 16 publications

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“…To obtain accurate structure parameters, firstly, we perform structural optimizations of the atomic positions and lattice constants for bulk selenium and tellurium with the conjugate gradient technique considering van der Waals interactions using SCAN [64,65], optB88-vdW [66], Perdew-Burke-Ernzerhof (PBE) [62], DFT-D2 [67] functionals, respectively. The calculated lattice con-stants based on SCAN functional agree rather well with that of experiments [57,58] compared to other theoretical calculations (see Table I). Therefore, in geometric optimization calculations, we adopt the SCAN functional for layered 2D structures, which was verified to be of sufficient accuracy in describing the structural properties of layered materials [54], to improve the description of van der Waals interactions between atomic chains.…”

Section: Structure and Computational Methodssupporting

confidence: 85%

“…1(a), 1(b) and 1(c). It consists of parallel-aligned helical chains arranged in a hexagonal array [57,58]. Every atom is covalently bonded to two neighboring atoms along each chain, and interacts weakly with atoms of the adjacent chains.…”

Section: Structure and Computational Methodsmentioning

confidence: 99%

“…1. It consists of the helical chains arranged in a hexagonal array [32,33]. The three atoms in the unit cell are situated at positions (u, 0, 0), (0, u, 1/3) and (−u, −u, 2/3).…”

Section: Structure and Computational Methodsmentioning

confidence: 99%

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Large second-harmonic generation and linear electro-optic effect in trigonal selenium and tellurium

Cheng

Zhu

et al. 2019

Phys. Rev. B

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Trigonal selenium and tellurium crystalize in helical chain-like structures and thus possess interesting properties such as current-induced spin polarization, gyrotropic effects and nonlinear optical responses. By performing systematic ab initio calculations based on density functional theory in the generalized gradient approximation plus scissors correction, we study their linear and nonlinear optical (NLO) properties. We find that the two materials exhibit significant second-harmonic generation (SHG) and linear electro-optic (LEO) effect. In particular, the SHG coefficients (χ (2) ) of tellurium are huge in the photon energy range of 0∼3 eV, with the magnitudes of χ(2) xxx being as large as 3640 pm/V, which are about sixteen times larger than that of GaN, a widely used NLO material. On the other hand, trigonal selenium is found to possesses large LEO coefficients rxxx(0) which are more than six times larger than that of GaN. Therefore, trigonal tellurium and selenium may find valuable applications in NLO and LEO devices such as frequency conversion, electro-optical switch and light signal modulator. The energy positions and shapes of the principal features in the calculated optical dielectric functions of both materials agree rather well with the available experimental ones, and are also analyzed in terms of the calculated band structures especially symmetries of the involved band states and dipole transition selection rules. *

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Section: Structure and Computational Methodssupporting

confidence: 85%

Section: Structure and Computational Methodsmentioning

confidence: 99%

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Large second-harmonic generation and linear electro-optic effect in trigonal selenium and tellurium

Cheng

Zhu

et al. 2019

Phys. Rev. B

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“…The calculated vDOS show pronounced similarities to the densities of states measured by inelastic neutron scattering for amorphous [83] and trigonal Se [84,85], and the trigonal form has also been studied theoretically. There are three atoms in the unit cell and nine phonon branches, and the identification of the acoustic branches with torsional vibrations, and the optical branches with bending (∼13 meV) and stretching (∼30 meV) nodes, has been carried over to the disordered phases as well.…”

Section: Power Spectrum Vibrational Dosmentioning

confidence: 53%

Density functional and classical simulations of liquid and glassy selenium

et al. 2020

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Molecular dynamics simulations of liquid and glassy selenium have been carried out using density functional (400-773 K, 600 atoms) and classical force field (290-500 K, 5488 atoms) methods. Structural features (structure factors, pair distribution functions, bond lengths, bond and dihedral angles, cavities) and dynamical properties (diffusion coefficients, power spectra, sound velocity, collective excitations, bond lifetimes) agree well with experimental data where available. The structures are predominantly chainlike, with a small fraction of rings with a range of sizes, and large cavity volumes lead to flexible chains. It is striking that the density functional simulations show very few Se 8 rings at 600 K and below.

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“…The unit cell of t-Se consists of three atoms, leading to a total of nine phonon branches: three acoustical and six optical [29,30]. The optical phonon frequencies of t-Se obtained by solving a secular equation at Γ-point are listed in Table 1 along with experimental data for comparison.…”

Section: Resultsmentioning

confidence: 99%