Born Effective Charge Tensors Research Articles

Polarized Raman, infrared and dielectric spectra of lead-free K0.5Na0.5NbO3 piezoelectric system: insights from ab-initio theoretical and experimental studies

The K0.5Na0.5NbO3 (KNN) system has emerged as one of the most promising lead-free piezoelectric over the years. In this work, we perform a comprehensive investigation of electronic structure, lattice dynamics and dielectric properties of room temperature phase of KNN by combining ab-initio DFT based theoretical analysis and experimental characterization. We assign the symmetry labels to KNN vibrational modes and obtain ab-initio polarized Raman spectra, Infrared reflectivity, Born-effective charge tensors, oscillator strengths etc. The KNN ceramic samples are prepared using conventional solid-state method and Raman and UV–Vis diffuse reflectance spectra are obtained. The computed Raman spectrum is found to agree well with the experimental spectrum. In particular, the results suggest that the mode in range ∼840–870 cm−1 reported in the experimental studies is longitudinal optical with A1 symmetry. The Raman mode intensities are calculated for different light polarization set-ups that suggests the observation of different symmetry modes in different polarization set-ups. The electronic structure of KNN is investigated and optical absorption spectrum is obtained. Further, the performances of DFT semi-local, meta-GGA and hybrid exchange-correlations functionals, in the estimation of KNN band gaps are investigated. The KNN bandgap computed using GGA-1/2 and HSE06 hybrid functional schemes are found to be in excellent agreement with the experimental value. The COHP, electron localization function and Bader charge analysis is also performed to deduce the nature of chemical bonding in the KNN. Overall, our study provides several bench-mark important results on KNN that have not been reported so far.

Diamond two-phonon infrared absorption spectrum calculated from first principles using the finite displacement method

We calculate the two-phonon contribution to the dielectric susceptibility of diamond at room and elevated temperatures, utilizing a general ab initio model that can be extended to higher n phonon processes. We calculate the second-order dipole moments using a finite displacement method to calculate the derivatives of the Born effective charge tensor. Specifically, we use results obtained from density-functional theory and density-functional perturbation theory in this finite displacement method to calculate the dipole moments of diamond in the two-phonon case. We use the calculated dipole moment to determine the contribution of two-phonon processes to the dielectric susceptibility. We then calculate the absorption curve as a function of wave-number at room or elevated temperatures. Our results indicate that the calculated absorption is in good agreement with previous calculations, and that it increases in magnitude with temperature while maintaining a consistent shape.

Thermal phonon modulation of III-nitride semiconductors under strong electric fields

Self-heating effects in high-power III-nitride semiconductor electronics and optoelectronic devices limit their practical applications, while phonon modulation can be used to alleviate heat dissipation problems. In this paper, we report our efforts to suppress macroscopic polarization fields when applying strong electric fields, which affect the phonon frequency. We investigate alterations in phonon frequencies for two materials, 2H-GaN and 2H-AlN, for various electric field strengths ranging from 0.00 V/Å to 0.07 V/Å and 0.00 V/Å to 0.18 V/Å, respectively. We also analyze the changes in the macroscopic dielectric tensor and the BORN effective charge tensor. The calculation results reveal that the vibration frequencies of the longitudinal-optical (LO) A1(LO) mode are decreased by approximately 2 cm−1 for 2H-GaN and 3 cm−1 for 2H-AlN. Our simulation results are consistent with the Raman spectroscopy results of Si-doped 2H-GaN specimens illuminated with 325 nm excitation for a variety of carrier concentrations. This study contributes to a better understanding of the factors influencing phonon behavior, thus offering new methods for optimizing the thermal regulation and dissipation patterns of III-nitride semiconductor materials and devices.

Electronic, Thermal, and Thermoelectric Transport Properties of ε-Ga2O3 from First Principles.

The electronic, thermal, and thermoelectric transport properties of ε-Ga2O3 have been obtained from first-principles calculation. The band structure and electron effective mass tensor of ε-Ga2O3 were investigated by density functional theory. The Born effective charge and dielectric tensor were calculated by density perturbation functional theory. The thermal properties, including the heat capacity, thermal expansion coefficient, bulk modulus, and mode Grüneisen parameters, were obtained using the finite displacement method together with the quasi-harmonic approximation. The results for the relationship between the Seebeck coefficient and the temperature and carrier concentration of ε-Ga2O3 are presented according to the ab initio band energies and maximally localized Wannier function. When the carrier concentration of ε-Ga2O3 increases, the electrical conductivity increases but the Seebeck coefficient decreases. However, the figure of merit of thermoelectric application can still increase with the carrier concentration.

Rotational g factors and Lorentz forces of molecules and solids from density functional perturbation theory

Applied magnetic fields can couple to atomic displacements via generalized Lorentz forces, which are commonly expressed as gyromagnetic $g$ factors. We develop an efficient first-principles methodology based on density-functional perturbation theory to calculate this effect in both molecules and solids to linear order in the applied field. Our methodology is based on two linear-response quantities: the macroscopic polarization response to an atomic displacement (i.e., Born effective charge tensor), and the antisymmetric part of its first real-space moment (the symmetric part corresponding to the dynamical quadrupole tensor). The latter quantity is calculated via an analytical expansion of the current induced by a long-wavelength phonon perturbation, and compared to numerical derivatives of finite-wavevector calculations. We validate our methodology in finite systems by computing the gyromagnetic $g$ factor of several simple molecules, demonstrating excellent agreement with experiment and previous density-functional theory and quantum chemistry calculations. In addition, we demonstrate the utility of our method in extended systems by computing the energy splitting of the low-frequency transverse-optical phonon mode of cubic SrTiO$_3$ in the presence of a magnetic field.

A first-principles investigation of the linear thermal expansion coefficients of BeF2: giant thermal expansion.

We present the results of a theoretical investigation of the linear thermal expansion coefficients (TECs) of BeF2, within a direct Grüneisen formalism where symmetry-preserving deformations are employed. The required physical quantities such as the optimized crystal structures, elastic constants, mode Grüneisen parameters, and phonon density of states are calculated from first-principles. BeF2 shows an extensive polymorphism at low pressures, and the lowest energy phases [α-cristobalite with space group (SG) P41212 and its similar phase with SG P43212] are considered in addition to the experimentally observed α-quartz phase. For benchmarking purposes, similar calculations are performed for the rutile phase of ZnF2, where the volumetric TEC (αv), derived from the calculated linear TECs along the a (αa) and c (αc) directions, is in very good agreement with experimental data and previous theoretical results. For the considered phases of BeF2, we do not find any negative thermal expansion (NTE). However we observe diverse thermal properties for the distinct phases. The linear TECs are very large, especially αc of the α-cristobalite phase and its similar phase, leading to giant αv (∼175 × 10−6 K−1 at 300 K). The giant αv arises from large Grüneisen parameters of low-frequency phonon modes, and the C13 elastic constant that is negatively signed and large in magnitude for the α-cristobalite phase. The elastic constants, high-frequency dielectric constants, Born effective charge tensors, and thermal properties of the above phases of BeF2 are reported for the first time and hence serve as predictions.

Lattice dynamics and dielectric properties of low-temperature phase of Y2SiO5

The previous experimental measurements showed that there is a problem for assigning the vibrational modes in the high frequency Raman spectra of the oxyorthosilicates, due to vibrational modes overlap. To solve this problem, we performed a lattice dynamical study of Y2SiO5 in monoclinic P21/c space group, using density functional perturbation theory. We found that three Ag modes at 840.3, 946.8 and 1012.5 cm−1 and three Bg modes at 847.47, 9 16.14 and 1035.57 cm−1 are due to asymmetric stretching internal vibrations of SiO4 tetrahedra υ3, while the Ag mode at 873.6 cm−1 and Bg mode at 864.26 cm−1 are due to symmetric stretching internal vibrations of SiO4 tetrahedra υ1. The phonon band structure and phonon density of states have been analyzed in terms of atomic contributions. IR-active modes with largest contribution to static dielectric constant were identified. The Born effective charge tensors have been calculated and discussed.

Significance of Coulomb interaction in interlayer coupling, polarized Raman intensities, and infrared activities in the layered van der Waals semiconductor GaSe

Two-dimensional (2D) layered III--VI semiconductors such as GaSe have attracted a lot of attention in recent years. Bulk GaSe consists of stacks of layers held together by weak interlayer interaction generally assumed to be of van der Waals type. However, proper justification of this assumption has been lacking in the reported studies. In this paper, we explore in detail the interlayer coupling in GaSe by studying lattice dynamics using first-principles density functional theory. Our study strongly suggests that contrary to common assumption, the contribution of Coulomb interaction in interlayer coupling can be significantly higher than that of van der Waals interaction in GaSe and other similar 2D layered semiconductors. The suggested predominance of electrostatic over van der Waals interaction in interlayer coupling may have important implications for various physical properties of GaSe and related layered semiconductors. Further, we study polarized Raman spectra, infrared (IR) activities, mode symmetry assignments, and Born-effective charge tensors for bulk GaSe polytypes (\ensuremath{\beta}, \ensuremath{\epsilon}, \ensuremath{\gamma}). The Raman mode intensities are calculated for different light polarization setups and signature Raman and IR active modes are identified for each GaSe polytype (structure). In addition, the influence of film thickness and strain on Raman and IR mode frequencies and intensities of GaSe are explored and compared with available experiments.

First-principles theory of infrared vibrational spectroscopy of metals and semimetals: Application to graphite

We develop an ab initio method to simulate the infrared vibrational response of metallic systems in the framework of time-dependent density functional perturbation theory. By introducing a generalized frequency-dependent Born effective charge tensor, we show that phonon peaks in the reflectivity of metals can be always described by a Fano function, whose shape is determined by the complex nature of the frequency-dependent effective charges and electronic dielectric tensor. The IR vibrational properties of graphite, chosen as a representative test case to benchmark our method, are found to be accurately reproduced. Our approach offers a first-principle scheme for the prediction and understanding of IR reflectance spectra of metals, that may represent one of the few available tools of investigation of these materials when subjected to extremely high-pressure conditions.

Analytic calculation and analysis of atomic polar tensors for molecules and materials using the Gaussian and plane waves approach.

The evaluation of atomic polar tensors and Born Effective Charge (BEC) tensors from Density Functional Perturbation Theory (DFPT) has been implemented in the CP2K code package. This implementation is based on a combination of the Gaussian and plane wave approach for the description of basis functions and arising potentials. The presence of non-local pseudo-potentials has been considered, as well as contributions arising from the basis functions being centered on the atoms. Simulations of both periodic and non-periodic systems have been implemented and carried out. Dipole strengths and infrared absorption spectra have been calculated for two isomers of the tripeptide Ser-Pro-Ala using DFPT and are compared to the results of standard vibrational analyses using finite differences. The spectra are then decomposed into five subsets by employing localized molecular orbitals/maximally localized Wannier functions, and the results are discussed. Moreover, group coupling matrices are employed for visualization of results. Furthermore, the BECs and partial charges of the surface atoms of a periodic (101) anatase (TiO2) slab have been investigated in a periodic framework.

Vibrational spectra of MO (M = Sn/Pb) in their bulk and single-layer forms: role of avoided crossing in their thermodynamic properties

We report ab-initio calculations of phonon dispersion relationship on bulk and single layers of SnO and PbO. In agreement with experimental observations of Raman spectroscopy measurement, we find that A1g mode is higher in frequency than Eg mode. Moreover, the reason behind the shift of A2u mode to higher frequency for monolayers of both SnO and PbO is clearly understood from our calculations. In addition to vibrational spectroscopy, we also find avoided crossing or Landau quasi-degeneracy between the longitudinal acoustics (LA) and low-energetic transverse optical (TO) modes in bulk form of both SnO and PbO and in monolayer SnO. The signature of such avoided crossing can be found in the variation of both specific heat and entropy with temperature. Although both specific heat and entropy decrease at the temperature corresponding to the crossing region, the specific heat value shows a kink in that region. In contrast, such lowering/kink in thermodynamic variables does not appear in monolayer PbO. The reason behind the crossing can be analysed using the concept of Born effective charge and dielectric tensor. To further verify the crossing, we calculate phonon group velocity for every band as a function of phonon wave vector for each of these oxides, where the role of avoided crossing has been clearly shown and explained.

Conduction Mechanism in 70Li2S-30P2S5 Glass by Ab Initio Molecular Dynamics Simulations: Comparison with Li7P3S11 Crystal.

The 70Li2S-30P2S5 glass is a promising solid-state electrolyte for all solid-state lithium-ion batteries. Nevertheless, understanding the Li+ conduction mechanism is limited because of the complex amorphous nature of the glass. Herein, we present an ab initio molecular dynamics study of the 70Li2S-30P2S5 glass using a long simulation run (800 ps), improving the general understanding of its structure, dynamics, and electronic polarizability by comparing the results to those of the Li7P3S11 crystals. The shape difference of the P2S74- between the Li7P3S11 crystal and 70Li2S-30P2S5 glass is clearly observed in P-S-P bond angle, indicating that the P2S74- units in the 70Li2S-30P2S5 glass are relatively free from stress for crystallographic ordering. From the Li trajectories for 800 ps, the diffusion within the limited space in the unit cell is derived as the effective porosity. The lower effective porosity in the 70Li2S-30P2S5 glass compared to the Li7P3S11 crystal implies that a part of volume in the 70Li2S-30P2S5 glass cannot contribute to Li+ conduction. This reduction is attributed to the rotational motion of PS43-, which is observed only in the 70Li2S-30P2S5 glass. The sulfur polarizability is thoroughly analyzed for isotropic and anisotropic span through the Born effective charge tensor. The uniformly anisotropic polarizability of sulfur in the 70Li2S-30P2S5 glass is a characteristic property, which cannot create fast Li+ conduction paths as that in Li7P3S11 crystal.

Measurement and ab initio Investigation of Structural, Electronic, Optical, and Mechanical Properties of Sputtered Aluminum Nitride Thin Films

Aluminum Nitrides (AlN) thin films have been deposited ‎on glass substrates using DC-magnetron sputtering technique for different back pressure. The piezoelectric and related properties of highly c-axis oriented AlN films fabricated by dc planar magnetron sputtering have been calculated. Experimental results show that highly c-axis oriented AlN films can be fabricated by dc planar magnetron sputtering. X-ray powder diffraction (XRD) technique shows that AlN thin films exhibit a hexagonal structure. Vienna Ab initio Simulation Package (VASP) within the framework of density functional theory (DFT) and generalized gradient approximation (GGA) was used to investigate the structural and electronic properties of hexagonal AlN structures. The experimental lattice parameters of the as prepared thin films are found to be in good agreement with ab-initio calculated parameters. UV–Vis spectrophotometer measurements are performed to investigate the optical properties of AlN thin films. We found that the refractive index of AlN thin films exhibits values ranging between 2.1 and 2.2. Furthermore, the elastic, piezoelectric and dielectric tensors of AlN crystal are calculated using VASP. The dynamical Born effective charge tensor is reported for all atoms in the unit cell of AlN. The value of the principle component of electronic contribution to the static dielectric tensor of AlN is found to be ≈ 4.68 that is in good agreement with the experimental static dielectric constant. In addition, clamped-ion piezoelectric tensor is calculated. The diagonal components of the piezoelectric tensor are found to be e_33=1.784 C/m^2 and e_31=-0.8 C/m^2. The large values of the piezoelectric coefficients show that polar AlN crystal exhibits a strong microwave piezoelectric effect. Furthermore, the components of the elastic moduli tensor are calculated. The extraordinary electronic, optical, piezoelectric and elastic properties make AlN thin films potential candidates for several opto-electronic, elastic, dielectric and piezoelectric applications.

First-Principles Calculation of Physical Tensors of α-Diisopropylammonium Bromide (α-DIPAB) Molecular Ferroelectric Crystal

We report accurate calculations of tonsorial elements of α-Diisopropylammonium bromide (α-DIPAB) molecular ferroelectric crystal. In particular, elastic, piezoelectric and dielectric tensors were calculated using Vienna ab initio simulation package (VASP) within the framework of density functional (DFT) theory. The determination of above parameters allows an accurate description of the energy landscape for modeling of realistic devices at finite temperatures. We determine the major physical tensors in energy expansion of total energy per volume of un-deformed crystal to provide experimentalists with valuable information for designing and fabrication of pyroelectric detectors, capacitors, piezoelectric ferroelectric memories, display devices, electro-optic devices, and ultrasound transducers based on α-DIPAB. The spontaneous polarization P_s was calculated using Berry phase approach and found to be 22.64 μC⁄〖cm〗^2 in agreement with reported theoretical value. The dynamical Born effective charge tensor is reported for all atoms in the unit cell of α-DIPAB to get a deeper insight into the bonding network. The neighboring layers of DIPA molecules were found to be strongly crenelated due to the strong short-ranged electrostatic repulsion between Br sites in the DIPAB crystal structure. The organization of species in DIPA molecular layer as well as in the bromine “stitching” layer is essential for accurate calculation of DIPAB elastic properties. Having understood the actual network bonding in α-DIPAB, we calculated the components of the elastic moduli tensor. Our results indicate that a Young’s modulus of 10-180 GPa and a shear modulus of 4-26 GPa were found. Thus, α-DIPAB phase has a great potential to be a terrific candidate for flexible electronic device applications. The value of the principle component of electronic contribution to the static dielectric tensor of α-DIPAB is found to be ≈ 2.5, i.e. 50% smaller than that in typical perovskite-based ferroelectrics. Therefore, α-DIPAB is anticipated to exhibit creative materials' innovations. It offers highly customized features for specific applications, including insulation on polymer thick film conductive inks in the manufacture of membrane switches and flex circuits. Furthermore, clamped-ion piezoelectric tensor is calculated. Our results indicate a reasonable piezoelectric response of this polar crystal making it a low cost attractive candidate for piezoelectric applications.

Identification of normal modes responsible for ferroelectric properties in organic ferroelectric CBDC

Structure and dynamics of hydrogen bonded organic ferroelectric CBDC (1-cyclobutene-1,2-dicarboxylic acid, C6H8O4) have been investigated using inelastic neutron scattering (INS) spectroscopy and first principles lattice dynamics. Vibrational modes of O–H–O bending, related with two different types of hydrogen bonds, inter and intra-molecular, are manifested as two sets of doublets in the range of 900–1400 cm−1 in the INS spectrum. First principles density functional theory (DFT) is used to assign these doublets to out-of-the-plane and in-plane vibrations of these two types of O–H—O bending modes. Correlating structure and dynamics we find that although the local structures of the hydrogen bonded protons are similar, their medium range order may influence their vibrational frequencies. Vibrational modes of non-hydrogen bonded protons also are assigned separately in the spectrum. Comparing the calculated and the experimental INS spectra it is predicted that hydrogen bonded O–H bonds are more anharmonic than non-hydrogen bonded C–H bonds. From the calculated Born effective charge tensor it is predicted that inter-molecular hydrogen bonds contribute more to the ferroelectric polarisation of CBDC than intra-molecular ones. A large LO-TO splitting of the O–H stretching mode at 2471 cm−1 is identified with the mode that has significant contribution to the ferroelectric polarisation. As this mode is sensitive to long range Coulomb interactions and is responsible for ferroelectric properties of the material, vibrational spectroscopy combined with DFT calculations is proposed as a characterisation tool to investigate ferroelectric properties in the CBDC molecular crystal.

Continuity of phonon dispersion curves in layered ionic materials

The coupling of lattice vibrations with macroscopic electric fields in ionic crystals is examined from first principles based on density functional theory and density functional perturbation theory. Our analyses show that the coupled optical phonon–photon modes are well represented by using the pure phonon modes evaluated at as a basis. In addition, we find that apparent ‘discontinuities’ and mode ‘disappearances’ in the phonon dispersion curves of ionic materials for in hexagonal and other anisotropic materials are caused by the directional dependence of the Born effective charge tensor which is responsible for this coupling. The full dispersion curves, including the phonon–photon transverse modes are shown to be continuous functions of wavevector. Our work in this report provides a promising tool for first principles evaluation of phonon polaritons that may be accessible to experiment. Explicit examples are explored for cubic and hexagonal BN; the calculated results are in good agreement with previous computational values and available experimental measurements.

Structural, Electronic, Mechanical, Thermodynamic, and Linear and Nonlinear Optical Properties of MoS2, MoSe2, and their MoS2xSe2(1−x) Alloys: Ab Initio Calculations

The Born effective charge tensors, high-frequency dielectric constants, phonon frequencies at Г symmetry point, and phonon dispersion curves of MoS2xSe2(1−x) (x = 0, 0.25, 0.5, 0.75, and 1) alloys are calculated based on density functional perturbation theory using optimized lattice parameters. The structural stability, stiffness, ductility, and plasticity of these alloys are explored in detail by calculating the polycrystalline structural properties. The calculated Born effective charges and Poisson’s ratio indicate the existence of a combination of ionic and covalent bonding between the transition metal and chalcogens in each layer. Based on the calculated phonon frequencies, the temperature dependence of the specific heat at constant volume, entropy, and Helmholtz free energy of MoS2xSe2(1−x) (x = 0, 0.25, 0.5, 0.75, and 1) alloys are calculated in the harmonic approximation. Structurally, the spatial inversion symmetry in the MoS2xSe2(1−x) (x = 0.25, 0.5, and 0.75) alloys is broken. This leads MoS2xSe2(1−x) (x = 0.25, 0.5, and 0.75) alloys to exhibit novel nonlinear optical properties that do not exist in the 2H-MoX2 (X = S, Se) compounds. So, the nonlinear optical properties are calculated by applying the 2n + 1 theorem to an electric-field-dependent energy functional. It is found that MoS2xSe2(1−x) (x = 0.25, 0.5, and 0.75) alloys exhibit remarkable large nonlinear optical susceptibility and electro-optic coefficients and would be promising candidates for use in nonlinear optical applications. Van der Waals interactions are included in all the first-principles calculations, to correctly describe the interaction between adjacent layers. The calculated lattice parameters, electronic energy bandgaps, phonon frequencies, and high-frequency dielectric constants of 2H-MoX2 (X = S, Se) compounds are in good agreement with available theoretical and experimental results.

Theoretical investigation of lattice dynamics, dielectric properties, infrared reflectivity and Raman intensity spectra of Nowotny chimney-ladder semiconducting silicide Ru2Si3

Abstract Semiconducting silicides are highly promising materials for applications in thermoelectric, photovoltaic and optoelectronic devices. Here, using ab-initio density functional theory, the lattice dynamics, dielectric properties, Infrared (IR) refletivity and Raman intensity spectra of Nowotny chimney-ladder semiconducting silicide Ru2Si3 are investigated. The zone-center phonon mode frequencies are found to be in the range 80–510 cm−1. The Born effective charge tensor, oscillator strength and Infrared activity is found to largest for the mode with frequency 422 cm−1 which is primarily contributed by displacements of Si atoms. The largest Raman activity is obtained for mode with frequency 479 cm−1 which is also dominated by vibrations of Si atoms. Modified Becke-Johnson (MBJ) exchange potential is used to compute the band gap of Ru2Si3 which improves the band gap by ∼8% as compared to that obtained using LDA. The computed Infrared reflectivity and Raman intensity spectra are expected to provide benchmark first-principles theoertical results for comparison with the experiments.

DFT study of the electronic properties and the cubic to tetragonal phase transition in RbCaF3

The structural, elastic, vibrational, and electronic properties of ${\mathrm{RbCaF}}_{3}$ in the cubic and low-temperature tetragonal phases have been studied at the ab initio level with density functional theory. Using various exchange-correlation functionals of the generalized gradient approximation for structural properties like the ${\mathrm{CaF}}_{6}$ octahedron rotational angle or ratio $c/a$ of the tetragonal lattice constants, it is found that the best agreement with experiment is obtained with the PBEsol and Wu and Cohen (WC) functionals. The fundamental band gap is calculated to be direct and indirect in the tetragonal and cubic phases, respectively. The relation between the cubic and tetragonal phases is studied by monitoring the cubic zone boundary soft mode phonon ${R}_{{15}^{\ensuremath{'}}}$ as well as the $c/a$ ratio and tilt angle. The results for the Born effective charge tensors are also reported in order to study the effect of the long-range Coulomb interactions. We also investigated the corresponding pressure driven phase transition at $T=0\phantom{\rule{4pt}{0ex}}\mathrm{K}$, which we observe to be of second order in contrast to the first-order character experimentally detected for the structurally similar high pressure transition at ambient temperature. Based on recently developed finite strain Landau theory, we offer a possible explanation for this peculiar change of character.

Ab initio study of the lattice dynamical and thermodynamic properties of SbXI (X= S, Se, Te) compounds

The Born effective charges, high-frequency dielectrics constants, vibrational and thermodynamics properties of paraelectric SbSeI, SbTeI, SbSI and ferroelectric SbSI phase have been calculated by ab-initio method within the local density approximation. The high-frequency dielectric and Born effective charge tensor components are analyzed within density functional perturbation theory. We find remarkably enhanced/reduced Born effective charges and anomalously high-frequency dielectric constants for SbXI compounds. The phonon dispersion spectra and density of phonon states of these compounds were acquired using the direct method based on calculated Hellmann-Feynman forces. A comparison with the phonon dispersion curves of SbXI compounds displays minor differences that can attributed to the atomic-mass difference among S, Se and Te. The Raman and infrared active phonon mode frequencies of compounds are predicted at the Γ point. The thermodynamic properties of these compounds such as the internal energy, Helmholtz free energy, entropy, heat capacity, and Debye temperature are also investigated and discussed in the framework of the harmonic approximation. The obtained results were compared with available experimental and other theoretical data.