Revised Perdew Burke Ernzerhof Research Articles

First-principles calculations on electronic, superconducting, mechanical, and thermodynamic properties for the superhard compound Tc2C under pressure

This study presents a theoretical investigation on the electronic, superconducting, mechanical, and thermodynamic properties of the superhard compound Tc2C up to 100 GPa. The investigation is conducted via the first-principles plane-wave pseudopotential method. Furthermore, to treat the exchange-correlation potential for the total energy calculations, the revised Perdew–Burke–Ernzerhof formulation stemming from the generalized gradient approximation is employed. The results suggest that Tc2C is a potential hard compound due to the robust covalent bonding between Tc and C atoms. Moreover, the electronic structure and electron–phonon coupling reveal that Tc2C is a superconducting material with Tc of 0.59 K at 0 GPa. Additionally, using the quasi-harmonic Debye model, the variation of crucial structural parameters, such as the volume thermal expansion coefficient, heat capacity, and isothermal bulk modulus and its pressure derivatives, is predicted in terms of temperature and pressure. The results demonstrate that temperature and pressure have contrasting effects on the volume thermal expansion coefficient and heat capacity, and the effect of temperature is larger than that of pressure, especially at low temperatures. The isothermal bulk modulus decreases with increasing temperature but increases with increasing pressure. The first and second pressure derivatives of the isothermal bulk modulus for Tc2C are not the assumed constants in the equation of state study at high pressures and temperatures. To our knowledge, this study presents the first quantitative theoretical prediction of the pressure and temperature dependence of the thermodynamic parameters for Tc2C, which is essential for understanding the basic physical properties of similar transition metal carbides.

Structural, electronic, optical and thermodynamic properties of AlAuO2 and AlAu094Fe006O2 compounds scrutinized by density functional theory (DFT)

In this study, density functional theory (DFT) simulations have been used to study the structural, electrical and optical properties of AlAuO2 and AlAu094Fe006O2. Initially, the estimated bandgap of AlAuO2 0.45, 0.486, 0.419 and 2.49 eV in Perdew-Burke-Ernzerhof (PBE), Revised Perdew-Burke-Ernzerhof (RPBE), PBE for solids (PBE sol) and Becke three-parameter Lee-Yang-Parr (B3LYP) method respectively while AlAu094Fe006O2 has a zero-band gap after 6 % Fe doping. Then, density of state (DOS) and partial density of state (PDOS) were studied to determine the characteristics of the various orbitals of AlAuO2. The bonding characteristics and thermal stability of this crystal are determined by the Mulliken population charge and thermos physical parameters. Band edge of AlAuO2 was calculated which revealed that the AlAuO2 has suitable oxidation and reduction potential to degrade the contamination. A remarkable absorption has recorded for both AlAuO2 and AlAu094Fe006O2 in visible and ultraviolet region and capability to utilize photocatalytic dye degradation and hydrogen production through water splitting.

First-principles calculations to investigate structural, optical and electronic properties of ZrO2, Zr0.93Si0.07O2 and Zr0.86Si0.14O2 for dye-sensitised solar cells applications

ABSTRACT Initially, density approximations and generalised gradient approximations (GGA) functional of DFT were executed to determine the electronic structure where the non-local functionals of GGA obtained more close value of reference value, so that GGA method was used to calculate the band structures, DOS, PDOS and optical properties of ZrO2, Zr0.93Si0.07O2 and Zr0.86Si0.14O2 using the Perdew–Burke–Ernzerhof (PBE), Revised Perdew–Burke–Ernzerhof (RPBE), Perdew Wang (PW91), and Wu-Cohen. The transferability of electrons is completely related to PseudoPotential (PP), where four methods, such as OTFG ultra-soft, OTFG norm-conserving, ultra-soft, and norm-conserving, were used in this study. Finally, the norm-conserving PP has been selected as the most accurate method for determination of electronic structure. In addition, to assess the nature of orbital, the DOS and PDOS were additionally simulated and even the optical properties of crystals were calculated. Furthermore, the chemical reactivity, such as HOMO and LUMO, quantum properties, is justified where doping can have a vast effect as well as the open circuit voltage (Voc) is increased after doping. Finally, the toxicity data from in silico study refers to us that these are non-toxic or non-carcinogenic materials with not readily biodegradable status.

The kinetics of the ice-water interface from abinitio machine learning simulations.

Molecular simulations employing empirical force fields have provided valuable knowledge about the ice growth process in the past decade. The development of novel computational techniques allows us to study this process, which requires long simulations of relatively large systems, with abinitio accuracy. In this work, we use a neural-network potential for water trained on the revised Perdew-Burke-Ernzerhof functional to describe the kinetics of the ice-water interface. We study both ice melting and growth processes. Our results for the ice growth rate are in reasonable agreement with previous experiments and simulations. We find that the kinetics of ice melting presents a different behavior (monotonic) than that of ice growth (non-monotonic). In particular, a maximum ice growth rate of 6.5 Å/ns is found at 14K of supercooling. The effect of the surface structure is explored by investigating the basal and primary and secondary prismatic facets. We use the Wilson-Frenkel relation to explain these results in terms of the mobility of molecules and the thermodynamic driving force. Moreover, we study the effect of pressure by complementing the standard isobar with simulations at a negative pressure (-1000bar) and at a high pressure (2000bar). We find that prismatic facets grow faster than the basal one and that pressure does not play an important role when the speed of the interface is considered as a function of the difference between the melting temperature and the actual one, i.e., to the degree of either supercooling or overheating.

Steric Hindrance of NH3 Diffusion on Pt(111) by Co-Adsorbed O-Atoms.

A detailed velocity-resolved kinetics study of NH3 thermal desorption rates from p(2 × 2) O/Pt(111) is presented. We find a large reduction in the NH3 desorption rate due to adsorption of O-atoms on Pt(111). A physical model describing the interactions between adsorbed NH3 and O-atoms explains these observations. By fitting the model to the derived desorption rate constants, we find an NH3 stabilization on p(2 × 2) O/Pt(111) of 0.147-0.014+0.023 eV compared to Pt(111) and a rotational barrier of 0.084-0.022+0.049 eV, which is not present on Pt(111). The model also quantitatively predicts the steric hindrance of NH3 diffusion on Pt(111) due to co-adsorbed O-atoms. The derived diffusion barrier of NH3 on p(2 × 2) O/Pt(111) is 1.10-0.13+0.22 eV, which is 0.39-0.14+0.22 eV higher than that on pristine Pt(111). We find that Perdew Burke Ernzerhof (PBE) and revised Perdew Burke Ernzerhof (RPBE) exchange-correlation functionals are unable to reproduce the experimentally observed NH3-O adsorbate-adsorbate interactions and NH3 binding energies at Pt(111) and p(2 × 2) O/Pt(111), which indicates the importance of dispersion interactions for both systems.

Comparative density functional theory study for predicting oxygen reduction activity of single-atom catalyst

It has been well established that nitrogen coordinated transition metal, TM-N4-C (TM = Fe and Co) moieties, are responsible for the higher catalytic activity for the electrochemical oxygen reduction reaction. However, the results obtained using density functional theory calculations vary from one to another, which can lead to controversy. Herein, we assess the accuracy of the theoretical approach using different class of exchange-correlation functionals, i.e., Perdew-Burke-Ernzerhof (PBE) and revised PBE (RPBE), those with the Grimme’s semiempirical dispersion correction (PBE+D3 and RPBE+D3), and the Bayesian error estimate functional with the nonlocal correlation (BEEF-vdW) on the reaction energies of oxygen reduction reaction on TM-N4 moieties in graphene and those with OH-termination. We found that the predicted overpotentials using RPBE+D3 are comparable and consistent with those using BEEF-vdW. Our finding indicates that a proper choice of the exchange-correlation functional is crucial to a precise description of the catalytic activity of this system.

Theoretical investigation of structural, electronic, optical and thermoelectric properties of GaAgO2 based on Density Functional Theory (DFT): Two approach

In this research we have investigated systematically, the structural, electronic, bonding, optical, thermodynamic aspects of the GaAgO2 crystal using first-principles computations based on the density functional theory (DFT). To begin, the bandgap energies of GaAgO2 crystal have estimated to be 0.640 eV and 0.768 eV using the Generalized Gradient Approximation (GGA) based on the Perdew–Burke–Ernzerhof (PBE) and Revised Perdew–Burke–Ernzerhof (RPBE) functional methods. The density of state and partial density of state of GaAgO2 were then simulated to determine the nature of the orbital of the Ga, Ag, and O atoms. The Mulliken population charge and electron density distributions have estimated to further elucidate the bonding nature of GaAgO2. The complex dielectric function, refractive index, reflectivity, absorption coefficient, loss function, and photoconductivity of GaAgO2 are all computed and analyzed in depth for the optical transitions. Additionally, come to the realization of it, the thermo-electronic and thermophysical features have been added to enable this crystal to absorb visible light and retain a stable thermal state, enabling them to be employed in optoelectronic devices such as lasers, solar cells, and even luminescence ones.

Toward accurate electronic, optical, and vibrational properties of hexagonal Si, Ge, and Si1−xGex alloys from first-principle simulations

A new hexagonal phase of Si1−xGex alloys have been successfully synthesized through efforts in recent reports. Utilizing the combined first-principle calculations and special quasi-random model, we precisely investigated the structural, electronic, optical, and vibrational properties of hexagonal Si and Ge and disordered hexagonal Si1−xGex random alloys. We found a large negative deviation between the calculated lattice constants within the revised Perdew–Burke–Ernzerhof for solids functional and the linear fitting results. The electronic structures obtained by using the Tran–Blaha modified Becke–Johnson exchange potential confirm that hexagonal Si1−xGex (x > 0.625) alloys present direct bandgaps. Through solving the Bethe–Salpeter equation, the linear optical spectra of hexagonal Si and Ge are demonstrated. We reveal that the peaks of complex dielectric functions are redshifted with the addition of Ge atoms. Also, the real and imaginary parts exhibit strong anisotropy, which makes hexagonal Si1−xGex alloys potentially useful as nonlinear crystals. The transition is allowed in the infrared region for the hexagonal Si1−xGex (x > 0.625) alloys, and the linear optical spectra can be continuously tuned over a wide range of frequency with Ge addition in the infrared region. Furthermore, density-functional perturbation theory calculations were carried out to predict the off-resonance Raman activity. The results suggest that the vibrational modes of the Si–Si bond exhibit a strong dependency on the compositions, which provides a useful way to identify the most probable atomic configurations of hexagonal Si1–xGex alloys in future experiments.

First-Principles Study of the Stabilization and Mechanical Properties of Rare-Earth Ferritic Perovskites (RFeO3, R = La, Eu, Gd)

Current research aims to investigate the mechanical properties of rare earth perovskite ferrites (RFeO3, R = La, Eu, Gd) utilizing density functional theory (DFT) calculations. Using the revised Perdew–Burke–Ernzerhof approximation for solids (PBEsol) approximation, the elastic constants, bulk, Young’s, and shear modulus, Poisson’s ratio, and anisotropic properties are calculated. The quantum theory of atoms in molecules (QTAIM) is employed to analyze the stability of chemical bonds in the structures subjected to an external loading. Based on these calculations, Fe-O and R-O bonds can be considered as nearly ionic, which is due to the large difference in electronegativity of R and Fe with O. Additionally, our results reveal that the charge density values of the Fe-O bonds in both structures remain largely outside of the ionic range. Finally, the mechanical response of LaFeO3, EuFeO3, and GdFeO3 compounds to various cubic strains is investigated. The results show that in RFeO3 by increasing the radius of the lanthanide atom, the mechanical properties of the material including Young’s and bulk modulus increase.

Electronic structures and optoelectronic properties of ATiOPO4 (A = H, Li, Na, K, Rb, Cs, Fr, NH4, Ag) compounds and their applications in water splitting, CO2 reduction, and photo-degradation

In this paper, we have presented a computational study on the crystal structures, electronic, and optical properties of the titanyl phosphate family (ATiOPO4, where A = H, Li, Na, K, Rb, Fr, NH4 and Ag). The lattice parameters and bandgaps were calculated with the Perdew-Burke-Ernzerhof (PBE), Revised Perdew-Burke-Ernzerhof (RPBE), Perdew Wang (PW91), Wu-Cohen (WC), and Perdew-Burke-Ernzerhof for solids (PBEsol) non-local functionals of the generalized gradient approximations (GAA). The PBEsol functional provided better results and closer to the experimental data of the ATiOPO4 compounds; and thus, this method was used to analyze the band structures, density of states, and optical properties. A comparison between the optical properties (dielectric function, refractive index, absorption coefficient, reflectivity, electron energy loss spectrum, and photoconductivity) of ATiOPO4 compounds were discussed. The potentials of valance band and conduction band edges were calculated and used to investigate the protentional applications of the ATiOPO4 materials in water splitting, CO2 reduction, and photo-degradation processes. The results obtained in our investigations show that many of the investigated ATiOPO4 semiconductors could be used as effective photocatalysts in these photocatalytic reactions.

First-Principles Investigation on the Structure and Electronic Properties of SrBPO5

The structure and electronic properties of SrBPO5 have been investigated by the first-principles method based on density functional theory (DFT). The Generalized Gradient Approximation (GGA) in the scheme of Revised Perdew–Burke–Ernzerhof (RPBE) were utilized as exchange correlation. The results demonstrated that the GGA/RPEB functional is a good method for simulating the crystal and electronic structures of SrBPO5. Electronic property analysis revealed that SrBPO5 is a direct gap semiconductor; both the B–O bonds and P–O bonds in SrBPO5 have covalent character.

Fundamental properties of scandium chalcogenides and their alloys: DFT study

The full-potential linearized-augmented plane wave calculations based on density functional theory are performed to study the structural, electronic, optical and thermodynamic properties of scandium chalcogenides ScX (X = S, Se, Te) and their ternary alloys at equilibrium as well as under pressure. The revised Perdew–Burke–Ernzerhof generalized gradient approximation (GGA) is used to calculate the structural properties. The electronic and optical properties are calculated employing the GGA and the modified Becke–Johnson (mBJ) approaches. Moreover, the calculated lattice parameters agree well with the experiment results. The structure NaCl-type (B1) of the scandium chalcogenides undergoes under pressure a structural phase transition to CsCl-type (B2) and ZnS-type (B3). The binary and ternary alloys indicate a metallic behavior using GGA and mBJ scheme. The interband contribution to the optical properties is investigated by calculating the dielectric parameters e1(ω), e2(ω) and the index of refraction n(ω). A quasi-harmonic Debye model is applied to calculate the thermal properties.

Relating Interfacial Order to Sum Frequency Generation with Ab Initio Simulations of the Aqueous Al2O3(0001) and (112̅0) Interfaces

We use density functional theory molecular dynamics simulations to investigate the structure, dynamics, and vibrational sum frequency generation (vSFG) spectra at the Al2O3(0001)–H2O and Al2O3(1120)–H2O interfaces. We find that the differences in the vSFG spectra between the two interfaces can be explained by significantly weaker surface–water interactions at the (0001) vs (1120) interface. The weaker interactions at the (0001) surface are caused by the flat surface plane and high density of OH groups, leading to a decoupling of the vibrational modes of the surface OH groups and H2O molecules. The (0001) vSFG spectrum thus displays two well-separated peaks at the near-neutral pH, in contrast to the vSFG spectrum of the corrugated (1120) interface, which has stronger surface–water interactions and thereby a narrower band in the vSFG spectrum with closely spaced peaks. By simulating the interfaces with both the Perdew–Burke–Ernzerhof (PBE)–Tkatchenko–Scheffler and revised PBE (RPBE) functionals, we find ...

Theoretical study of structural, electronic and optical properties of novel ternary alloys $$\hbox {MgO}_{1-{x}}{\hbox {Se}}_{{x}}$$ MgO 1 - x Se x ( $$x =$$ x = 0.25, 0.50 and 0.75)

We report on the investigation of the structural, electronic, and optical properties of binary compounds (MgO and MgSe) and their ternary $$\hbox {MgO}_{1-{x}}\hbox {Se}_{{x}}$$ ( $$x=0.25, 0.5, 0.75$$ ) alloys within the density functional theory based on the full-potential linearized augmented plane wave method as implemented in the WIEN2k code. We have used the revised Perdew–Burke–Ernzerhof generalized gradient approximation (GGA-PBEsol) to calculate the structural properties and analyze the effect of the Se composition on the lattice constant and the bulk modulus of $$\hbox {MgO}_{1-{x}}\hbox {Se}_{{x}}$$ . The calculated electronic properties by employing the GGA-PBEsol and TB-mBJ approaches show that $$\hbox {MgO}_{1-{x}}\hbox {Se}_{{x}}$$ alloys have a direct band gap $$\Gamma $$ – $$\Gamma $$ for $$x = 0, 0.25, 0.5$$ and 0.75, suggesting the possibility of their use in the long wavelength optoelectronic applications. The optical properties such as the real and imaginary parts of the dielectric function, the refractive index, and the reflectivity of $$\hbox {MgO}_{1-{x}}\hbox {Se}_{{x}}$$ are computed by using the accurate TB-mBJ potential. The wide band gaps larger than 3.1 eV mean that $$\hbox {MgO}_{1-{x}}\hbox {Se}_{{x}}$$ alloys can be used in the applications of the ultraviolet region of the spectrum. Our data for all studied bowing parameters of $$\hbox {MgO}_{1-{x}}\hbox {Se}_{x}$$ may serve as references for future experimental studies.

Structural evolution of gypsum under high pressure: single-crystal X-ray experiments revisited

The structures of gypsum at pressures up to approximately 4 GPa are studied with density functional theory (DFT) and thoroughly compared with single-crystal X-ray diffraction experiments reported in the literature [Comodi et al. in (Am Miner 93:1530–1537, 2008)]. It is found that the exchange–correlation density functional revPBE (revised Perdew–Burke–Ernzerhof) in conjunction with a nonlocal van der Waals (vdW) correction is capable of modeling the lattice constants, axial compressibility, and bulk modulus with good accuracy, suggesting that the inclusion of the vdW functional is crucially important for understanding the structure of hydrous minerals. To gain further physical insights, the geometric parameters associated with the constituting components of gypsum (water molecules, SO4 tetrahedra, and CaO8 polyhedra) are analyzed and compared with the experimental values. DFT simulations show that, under pressure, the polyhedral layers remain as nearly planar sheets of interconnecting SO4 tetrahedra and CaO8 polyhedra without further crinkling. DFT analysis on the layer compressibility along the major crystal axis reveals that, in contrast to experimental reports, the hydrous interlayer is less compressible than the polyhedral layer. Squeezed by the lateral pressure, the water molecules in the hydrous interlayer become better affixed along the major axis, making the interlayer harder to compress along this axis.

Robustness of surface activity electronic structure-based descriptors of transition metals.

Efficient yet simple electronic structure-based descriptors of transition metal surfaces are key in material design for many scientific fields in research and technology. Density functional theory-based methods provide the framework to systematically explore the performance and transferability of such descriptors. Using appropriate surface models and the Vosko-Wilk-Nussair (VWN), Perdew-Burke-Ernzerhof (PBE), PBE adapted for solids (PBEsol), revised PBE (RPBE), and Tao-Perdew-Staroverov-Scuseria (TPSS) exchange-correlation functionals, we study the transferability of three descriptors: the d-band centre, the width-corrected d-band centre, and the Hilbert transform highest peak, among the low-index Miller surfaces for the metals of transition elements. We show that the d-band centre and the width-corrected d-band centre descriptors are almost independent of the functional used whereas a dependency is seen in the Hilbert transform highest peak. Moreover, it is seen that the differences between the surface descriptor values and predictions from the bulk ones are affected by the presence of surface states. Interestingly, a direct relation between the surface coordination number and the d-band centre electronic descriptor is found when surface states are absent.

Jacob's Ladder as Sketched by Escher: Assessing the Performance of Broadly Used Density Functionals on Transition Metal Surface Properties.

The present work surveys the performance of various widely used density functional theory exchange-correlation (xc) functionals in describing observable surface properties of a total of 27 transition metals with face-centered cubic (fcc), body-centered cubic (bcc), or hexagonal close-packed (hcp) crystallographic structures. A total of 81 low Miller index surfaces were considered employing slab models. Exemplary xc functionals within the three first rungs of Jacob's ladder were considered, including the Vosko-Wilk-Nusair xc functional within the local density approximation, the Perdew-Burke-Ernzerhof (PBE) functional within the generalized gradient approximation (GGA), and the Tao-Perdew-Staroverov-Scuseria functional as a meta-GGA functional. Hybrids were excluded in the survey because they are known to fail in properly describing metallic systems. In addition, two variants of PBE were considered, PBE adapted for solids (PBEsol) and revised PBE (RPBE), aimed at improving adsorption energies. Interlayer atomic distances, surface energies, and surface work functions were chosen as the scrutinized properties. A comparison with available experimental data, including single-crystal and polycrystalline values, shows that no xc functional is best at describing all of the surface properties. However, in statistical mean terms the PBEsol xc functional is advised, while PBE is recommended when considering both bulk and surface properties. On the basis of the present results, a discussion of adapting GGA functionals to the treatment of metallic surfaces in an alternative way to meta-GGA or hybrids is provided.

HCl dissociating on a rigid Au(111) surface: A six-dimensional quantum mechanical study on a new potential energy surface based on the RPBE functional.

The dissociative chemisorption of HCl on the Au(111) surface has recently been an interesting and important subject, regarding the discrepancy between the theoretical dissociation probabilities and the experimental sticking probabilities. We here constructed an accurate full-dimensional (six-dimensional (6D)) potential energy surface (PES) based on the density functional theory (DFT) with the revised Perdew-Burke-Ernzerhof (RPBE) functional, and performed 6D quantum mechanical (QM) calculations for HCl dissociating on a rigid Au(111) surface. The effects of vibrational excitations, rotational orientations, and site-averaging approximation on the present RPBE PES are investigated. Due to the much higher barrier height obtained on the RPBE PES than on the PW91 PES, the agreement between the present theoretical and experimental results is greatly improved. In particular, at the very low kinetic energy, the QM-RPBE dissociation probability agrees well with the experimental data. However, the computed QM-RPBE reaction probabilities are still markedly different from the experimental values at most of the energy regions. In addition, the QM-RPBE results achieve good agreement with the recent ab initio molecular dynamics calculations based on the RPBE functional at high kinetic energies.

A New Type of Scaling Relations to Assess the Accuracy of Computational Predictions of Catalytic Activities Applied to the Oxygen Evolution Reaction

AbstractExperimentally, it is well known that the overpotentials for the oxygen evolution reaction (OER) on RuO2 and IrO2 are similar and rather low. The question is whether widespread computational electrochemistry models based on adsorption thermodynamics are capable of reproducing such observations. Making use of DFT results of revised Perdew–Burke–Ernzerhof (RPBE) and Perdew–Burke–Ernzerhof (PBE) functionals from six different codes and various types of pseudopotentials, we show that whereas IrO2 is consistently predicted to have low overpotentials, RuO2 is predicted to have large overpotentials. A new methodology based on adsorption‐energy scaling relations shows that the inaccurate prediction for RuO2 stems from its anomalous adsorption energies of oxygen/oxygenates. Including explicit water solvation and using functionals that account for van der Waals interactions such as vdW‐DF, vdW‐DF2 and optPBE‐vdW modifies appropriately the adsorption energies so that both oxides are predicted to be highly active.

First-principles calculations of the electronic and structural properties of GaSb

In this paper, we carried out first-principles calculations in order to investigate the structural and electronic properties of the binary compound gallium antimonide (GaSb). This theoretical study was carried out using the Density Functional Theory within the plane-wave pseudopotential method. The effects of exchange and correlation (XC) were treated using the functional Local Density Approximation (LDA), generalized gradient approximation (GGA): Perdew–Burke–Ernzerhof (PBE), Perdew-Burke-Ernzerhof revised for solids (PBEsol), Perdew-Wang91 (PW91), revised Perdew–Burke–Ernzerhof (rPBE), Armiento–Mattson 2005 (AM05) and meta-generalized gradient approximation (meta-GGA): Tao–Perdew–Staroverov–Scuseria (TPSS) and revised Tao–Perdew–Staroverov–Scuseria (RTPSS) and modified Becke-Johnson (MBJ). We calculated the densities of state (DOS) and band structure with different XC potentials identified and compared them with the theoretical and experimental results reported in the literature. It was discovered that functional: LDA, PBEsol, AM05 and RTPSS provide the best results to calculate the lattice parameters (a) and bulk modulus (B 0); while for the cohesive energy (E coh), functional: AM05, RTPSS and PW91 are closer to the values obtained experimentally. The MBJ, Rtpss and AM05 values found for the band gap energy is slightly underestimated with those values reported experimentally.