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In this comment, a Sagdeev pseudopotential analysis is used to illustrate signficant errors in the paper entitled “Dust-Ion-Acoustic Waves in unmagnetized 4-component plasma” [Adv. Space Res. 67, 1244–1253 (2021)]. It is shown that this is due to an erroneous formulation of the moving frame used for the reductive perturbation analysis. The correct derivation is provided in detail. The significance of the near-supercritical compositional criterion is also illustrated.

Understanding the physics of droplet collisions is of crucial importance in many industrial processes such as inkjet printing, spray cooling, and spray combustion. In this paper, a modified multiple-relaxation-time pseudopotential multiphase lattice Boltzmann model is proposed to investigate binary droplet collision with different collision angles. The surface tension can be adjusted independently under the condition of high Reynolds number and large density ratio using this model. Then the model validation is performed by simulating three benchmark cases including stationary droplet, oscillating droplet, and capillary wave instability, respectively. Finally, different regimes of binary droplet collision are presented, and collision features such as liquid filament and satellite droplet are investigated at collision angles of 30°, 60°, 90°, 120°, and 150°. The results show that there is no liquid filament or satellite droplet at the collision angle of 30°, yet both of them appear as the angle increases. When the collision angle is 60°, the percentage of satellite droplet to liquid phase reaches 30%, while the proportions are less than 10% at collision angles of 90°, 120°, and 150°. Besides, two break-up mechanisms of “end-pinching” and capillary wave instability are inspected. It is found out that the back-flow phenomena at the joints of droplets and the liquid filament are caused by the “end-pinching” mechanism, which further leads to the capillary wave instability of the liquid filament.

A theoretical study is presented for the propagation of Dust Ion Acoustic Waves in an unmagnetized four-component plasma, consisting of Maxwellian negative ions, cold mobile positive ions, $\kappa$-distributed electrons and positively charged dust grains. Based on the characteristics of Sagdeev pseudopotential and phase portraits, three types of nonlinear waves are observed --- solitons, double layers and supersolitons. The conditions for the existence of such nonlinear waves are highly sensitive to the plasma parameters. The results obtained in this study may be of wide relevance in the field of space plasma as well as ultrasmall semiconductor devices in the laboratory., Comment: 20 pages, 6 figures

A well-recognized local pseudopotential is utilized to study the electrical transport properties such as electrical resistivity ( ρ ), thermal conductivity ( σ ) and thermoelectric power ( TEP ) of some liquid metals. The model potential theory in combination with Ziman, mean free path and Kubo models are implemented in the aforesaid study. The Taylor’s local field correction function is taken for studying the exchange and correlation effect with one component plasma (OCP) structure factor method of liquid metals. The computed data is found highly appreciated order with available either theoretical or experimental outcomes wherever exits.

The collective mode excitations of Zr41Ti14Cu12.5Be22.5Fe10 bulk metallic glass (BMG) have been theoretically studied at room temperature by applying pseudopotential technique. A well-known Shaw’s optimized constant core model pseudopotential with five different forms of local field correction functions given by Hartree (H), Taylor (T), Ichimaru-Utsumi (IU), Farid et al. (F) and Sarkar et al. (S) are used to study the screening effects on the aforementioned work. The phonon dispersion curves (PDCs) are computed by using Hubbard-Beeby (HB) theoretical approach. While, elastic and thermodynamic properties are theoretically calculated from the elastic limit of the phonon dispersion curve. Such properties compared well with available data in the literature and are found qualitative agreement with them.

Density functional theory is increasingly used to predict and understand the properties of hydrogen storage materials. Many such calculations have been performed for various real and hypothetical palladium hydrides, yet despite excellent agreement on electron band structures, significant disparities persist in relation to phonon band structures and critical matters such as dynamic stability of alternative structures. Some disparities may arise because of differing computation approaches between researchers. Therefore in this work a systematic approach was followed to compare calculated electron and phonon band structures for four palladium hydrides: PdH and Pd3VacH4 (the superabundant vacancy phase) assuming that octahedral (oct) or tetrahedral (tet) lattice interstices are occupied by H, with six commonly used calculation schemes based on the local density approximation and the generalised gradient approximation, within the harmonic approximation. Of the twenty-four combinations tested, seven are new to the literature. Excellent agreement was found between the calculation schemes for the electron band structures of all four crystal structures. The position regarding phonons is much less satisfactory, however, and highlights the sensitivity of phonon properties to the calculated lattice constants. None of the calculation schemes could reproduce the measured phonon energy gap of PdH(oct) and it is necessary to include anharmonicity of the H potential to obtain realistic results. The calculated lattice constants of PdH(tet) were larger than any observed in experiments, although the structure is dynamically stable. All six calculation schemes predicted dynamic instability for Pd3VacH4(oct), although the calculated lattice constant agreed with the estimated zero-temperature experimental value. This structure requires new calculations accounting for anharmonicity. The calculated lattice constant for Pd3VacH4(tet) was larger than any experimental value, so this alternative, while dynamically stable, is certainly not observed.

The collective modes of Zr41Ti14Cu12.5Be22.5Fe10 bulk metallic glass (BMG) have been theoretically studied using pseudopotential formalism. Shaw’s optimized model potential is used to describe effective interactions. Five different forms of the local field correction functions, viz. Hartree (H), Taylor (T), Ichimaru-Utsumi (IU), Farid et al. (F) and Sarkar et al. (S) have been exploited with modified Bhatia-Singh (BS) computational approach to examine the relative influence of exchange and correlation effects and to reproduce longitudinal and transverse modes of phonon eigenfrequencies using phonon dispersion curves (PDCs). Important thermodynamic and elastic properties are calculated by long-wavelength limits of phonon modes. The comparisons of such properties with earlier reported data are shown good agreement.

Oxidation of Al (O2 or H2O) is an important chemical interaction in electrochemistry, heterogeneous catalysis and metal corrosion [1] , [2] . Investigations on chemisorption and sorption of O2 and H2O molecules are of great importance, as these are fundamental steps in the oxidation of Al. We studied the adsorption behavior of H2O and O2 on Al surfaces and estimated adsorption and diffusion of H on the Al surface. The main methods of research are theoretical calculations based on the theory of the functional of electronic density and the theory of pseudopotential. It has been shown that O and H atoms can be adsorbed on surface of Al (1 0 0), where adsorption takes place on three different initial adsorption sites (above the atom, between the atoms and the interatomic void), and their adsorption energy increases with an increasing O. The migration of the H atom is lighter on the surface than in the inner layer, and the H atom must be overcome by a higher energy barrier to pass from the surface to the subsurface layer.

The electronic and optical features of InSb spherical quantum dots have been investigated by a pseudopotential approach as a function of their radius taken in the range 1-10 nm. The direct- and indirect band gaps along with the electron and heavy hole effective masses are all found to be diminished as the quantum dot radius is increased. However, the refractive index, the static- and high frequency dielectric constant as well as the transverse effective charge are shown to be augmented by increasing the quantum dot radius. It is noted that the quantum confinement is of great impact on all the studied quantities for quantum dot radius below 6 nm. This could result in more opportunities to obtain desired optoelectronic properties that cannot be obtained in the bulk InSb materials.

In this paper, the structural, elastic, electronic properties of Ru2CrZ (Z=Si, Ge, Pb, Sn) are explored using the generalized gradient approximation based on ab initio plane-wave pseudopotential density functional theory. With the help of the quasi-harmonic Debye model, we also investigate the variation of normalized volume V/V0, the heat capacities CV and CP, thermal expansivity, and Debye temperature of Ru2CrZ (Z=Si, Ge, Pb, Sn). Results show that the Cu2MnAl type structure is more stable then Hg2CuTi type structure. The four compounds in the ground state are predicted to be nearly half-metal behavior with total magnetic moment near to the integer value. To provide a comparative and complementary study to future researches, we investigated the elastic and thermodynamic properties.

The size-dependent energy gaps, electron and heavy hole effective masses, phonon frequencies and polaron related parameters in InSb spherical quantum dots are investigated. The calculations are performed using a pseudopotential approach. Good agreement is obtained between our results and those of the literature for bulk InSb. When proceeding from bulk to nano-scale, all studied properties are found to be changed significantly. This is attributed to the quantum confinement effect.

The effects of including the exchange interaction (J) and Hubbard on-site Coulombic interaction (U) on the structural parameters and magnetic moment of Mn-doped ZnO were explored. The calculations were performed with the plane-wave pseudopotential method along with generalized-gradient approximations (GGA). Using the GGA+U + +J method by applying Hubbard corrections Ud to the Zn 3d states and Up to the O 2p states, the lattice constants were calculated for various reported Hubbard parameters. The difference in the lattice constants between the calculated results and experimental measurements is within 1% for pure ZnO and pure MnO. This study considers three cases: (i) substitution of Mn for Zn, (ii) substitution of Mn for Zn combined with Zn vacancy, and (iii) substitution of Mn for Zn with O vacancy. Results are shown that the system is ferromagnetic (FM) when zinc vacancies are present. For three cases with oxygen vacancies, only one of them is FM. It was also found that the Hubbard U and exchange interaction J improved the calculated results, allowing it to exhibit good agreement properties for Mn-doped ZnO with the experimental data.

The calcium chalcogenides belong to an important class of semiconductor materials. It comprises a large band gap which enables its use in applications of luminescent devices, so they are of technological and scientific interest. These compounds are found in NaCl (B1) and CsCl (B2) crystallographic phase. In the current work, structural properties of calcium chalcogenides have been studied to understand their phase stability. Here, these properties are computed by applying the plane wave pseudopotential method employing a generalized gradient approximation (GGA) of the density functional theory (DFT). In addition to this an effort is also made to plot the phonon density of state (PDOS) and phonon dispersion spectra of this compound to understand the phonon behavior and are compared with other calculated results.

In this work, first-principles computational study on the structural, electronic and optical properties of Tl4GeS3, Tl4GeSe3 and Tl4GeTe3 ternary compounds are presented. The computations are performed with pseudopotential plane wave method based on density functional theory with the generalized gradient approximation of Perdew–Burke and Enzerhof (PBE-GGA). The calculated structural, electronic and optical parameters are consistent with the available experimental results. The computed electronic band structures confirm the semiconducting nature for these compounds with direct band gaps of 0.17 eV, 0.085 eV and 0.015 eV for Tl4GeS3, Tl4GeSe3 and Tl4GeTe3, respectively. Furthermore, the electron charge density distribution indicated that the nature of bonds between Ge and S/Se/Te are covalent nature, whereas Ge and S/Se/Te anions formed ionic bonds. The optical parameters revealed that Tl4GeS3, Tl4GeSe3 and Tl4GeTe3 are highly dielectric materials and has the potential to be beneficial in the optoelectronic device applications. Keywords: Band gap, Density of states, Optical properties, Density functional theory

The pseudopotential based formulation proposed by MacMillan used for studying the superconductivity through five most important superconducting state parameters given by the electron-phonon coupling strength λ g , the Coulomb interaction parameter μ g ∗ , the transition temperature T Cg , the isotope effect exponent α g and the effective interaction strength N O V g of Fe X Zr 1 - X I n 1 - X T l X ( X = X = 20, 24, 25, 27 and 28) metallic glasses are reported in the present study. Our well-defined pseudopotential with five different types of exchange and correlation functions due to Hartree (HRT), Taylor (TYR), Ichimaru-Utsumi (ICUM), Farid and co-workers (FHER) and Sarkar and co-workers (SSHR) are utilized in the current computation for observing the screening influences on the aforementioned parameters. It is also seen from the present investigation that two parameters λ g and T Cg are shown quite sensitive to the exchange and correlation functions in comparison with the other three parameters. A linear T Cg -equation for ICUM function shows an excellent agreement with experimentally available data of the earlier work. Such type of outcomes supports the superconducting nature in the said metallic glasses.

The collective dynamics for the longitudinal as well as the transverse modes of the phonon eigenfrequencies are carried out for three Zr-based bulk metallic glasses (BMGs) in the present paper by employing pseudopotential theory. The theoretical phonon models proposed by Hubbard-Beeby (HB), Takeno-Goda (TG) and Bhatia-Singh (BS) are used to generate the phonon dispersion curves (PDC). The elastic and thermodynamic properties have also been investigated for the said BMGs by using the elastic limit of the phonon dispersion curves. The screening impact was also observed by using five different forms of local field functions due to Hartree (H), Taylor (T), Ichimaru and Utsumi (IU), Faridet al. (F) and Sarkaret al. (S) for the aforesaid properties. The derived results are seen to be in qualitative agreement with the available experimental and theoretically calculated data, as they confirm the applicability of Shaw's constant core model potential and self-consistent phonon theory for such studies.

Bimetallic selenocyanate complex ZnCd(SeCN)4 (ZCSC) crystals are a novel material with ultraviolet nonlinear optical (NLO) properties. To the best of our knowledge, theoretical studies on these complexes have mostly focused on the microcosmic NLO responses of single complex molecular system and ignored their macroscopic NLO effects. In this paper, the geometric structure of ZCSC crystal was optimized on the basis of first principle, and the electronic band structure and linear optical (LO) properties were investigated via pseudopotential plane wave method. The macroscopic NLO properties of ZCSC crystal were evaluated through the combination of density functional theory and a devised anionic group method for the first time, and good agreement with the experimental results was obtained. The absorption spectrum of ZCSC was located at 95–325 nm, and the NLO properties were mainly caused by the transitions of electronic states from N2p and Se3p valence bands to C2p, N2p, Se3p, and Cd4p conduction bands. Results showed that the second-order NLO coefficients were d14 = 2.304–3.55 pm/V and d15 = 8.07–9.91 pm/V, showing an evident increase compared with those of ZnCd(SCN)4 crystals.

In this work primarily structural parameters of the Y3Al2 was optimized. In the calculations, PBE type Exchange-Correlation function was selected in the GGA approximation and ultra-soft pseudopotential was used. Crystalline lattice parameters a = 15.581 Bohr, c / a = 0.923. Total energy was calculated by small deformations in volume. These values were fitted to the equation of state and the bulk modulus was calculated as 58.4 GPa. The working structure has elastic constants as C11, C12, C13, C33, C44 and C66. These constants have been calculated under ambient pressure. Using the elastic constants, bulk, shear, Young modulus and Poisson ratio (in Voigt approach) were obtained as 58.12, 34.31, 86.01 GPa and 0.25, respectively. Melting temperature of the material was guessed from the elastic constant. The results were compared with the current experimental and theoretical data.

The structural and electronic properties of InAsxSb1-x ternary alloys are studied using plane-wave pseudopotential method based on the density functional theory. The Born effective charge, elastic constants, phonon dispersion curves, linear and nonlinear optical properties of these compounds are calculated using density functional perturbation theory. Based on the calculated phonon frequency, the specific heat at constant volume and entropy are obtained within the harmonic approximation. Moreover, due to the density functional theory band gap problem, the band gap correction is performed within the one-shot GW approximations. The distinguished role of In 4d states on the electronic energy band gap and nonlinear properties of these alloys are extensively explored by the comparison between the calculated results of Hartwigsen-Goedecker-Hutter and Trouiller-Martins-type pseudopotentials. The calculated results show that InAsxSb1-x alloys are mechanically stable and can be a good candidate for high-performance nonlinear optical material. The calculated results of InAs and InSb compounds are in acceptable agreement with available theoretical and experimental results, so the calculated results of InAsxSb1-x alloys will be helpful for future experimental and theoretical investigations.

The electronic structures and optical properties of La, C-codoped TiO2 were investigated by the first-principles plane-wave ultrasoft pseudopotential method. Our calculations suggest that the micro-structures of La-C codoped system is different from that of TiO2, and the hole effective mass is increased by La-doping, which can create holes in the valence band; Nonmetal C doping can narrow the band gap of TiO2 and enhance the photo-catalytic activity by the formation of localized mid-gap state originated from C 2p states above the top of the valence band; Metal La and nonmetal C co-doping could induce a synergistic effect, the doping of La atoms leads the redistribution of C 2p states in C atoms, which provide more electrons to participate into the 3d states of Ti atoms. The charge compensation effects between Ti 3d and C 2p produce impurity levels, which reduce the band gaps and enhance the carrier concentration, meanwhile La ions are not easy to enter the lattice of TiO2, which may form hetero-junction structure of La2O3-TiO2 with better dispersion in the bulk phase of TiO2 to limit the recombination of photo-generated electron hole pairs. The calculated results of optical properties show that C-TiO2 and La-C-TiO2 systems exhibit good visible absorption and the doping is beneficial to the propagation of light in the doped TiO2.

Ab initio pseudopotential density functional calculations of location-dependent Stone-Wales (SW) defect are performed to investigate the electronic and optical characteristics of (10,0) zigzag-edged hybrid Carbone/Boron-Nitride (C/BN) heteronanotubes which recently have been proposed to exhibit promising properties. These heteronanotubes are circumferentially formed from two curled carbon and boron nitride nanoribbons. Here, we report a systematic study on the effective role of SW defect located at different radial positions along the heteronanotube. The calculated band gap of the structures and also SW formation energies reveal that the defects preferentially localize at the very interface of the BN and graphene segments. Moreover, the critical importance of the boundary-oriented SW defect (either BN or graphene edges) is comprehensively studied using optical absorption spectra, electron charge density 2D maps, and bonding configurations of occupied/unoccupied π orbitals corresponding to the B–C/C–N bonds. Our results provide new insights into the band gap engineering of C/BN heterostructures which are the potential candidate for the future optoelectronic applications.

Based on first-principles pseudopotential plane-wave method within the generalised gradient approximation, I have studied the structural, electronic, vibrational and BCS superconducting properties of BaIr2As2. The calculated electronic structure and density of states suggest that the bonding is a combination of covalent, ionic and metallic in nature and that the Fermi level falls in one of the peaks in the electronic density of states. The electron–phonon interaction calculations suggest that the mechanism for superconductivity is heavily governed by interactions of electrons with acoustic phonon modes and low-frequency optical phonon modes. By integrating the Eliashberg spectral function, the value of average electron–phonon coupling parameter is found to be 0.64 and the superconducting critical temperature is calculated to be 2.337 K, in excellent agreement with the experimentally reported value of 2.450 K.

The hybrid HF/DFT functionals in conjunction with small-core pseudopotential have been employed to investigate the geometric and electronic structures of small ThCn (n = 1–7) clusters. The fan-type isomers were found to be more stable than the linear ones. Analyses on the incremental binding energies indicate that the clusters with even C atoms possess the higher stability than odd-numbered ones. The interaction natures of Th-C chemical bonds were revealed by the methods of bond overlap density of states (OPDOS), adaptive natural density partitioning (AdNDP) and electron localization function (ELF).

We conduct a theoretical, first-principles study of thallium sulfide with the space group FM-3M. We determine the electronic structure, phonon dispersion relations, Eliashberg spectral function, electron-phonon coupling constant (λ) and any superconductivity. The results indicate that this structure is characterized by a much larger electronic density of states at the Fermi level. Both the norm-conserving pseudopotential and ultra-soft pseudopotential are used to study its superconducting properties. The transition temperatures (Tc) for superconductivity are 9.3 K and 4.2 K, while the electron–phonon coupling constants are 0.79 and 0.59, respectively. Tc does not increase with increasing pressure. The superconductivity disappears when the pressure reaches 80 GPa.

First-principles calculations have been performed on lithium borohydride LiBH4 using the ultrasoft pseudopotential method, which is a potential candidate for hydrogen-storage materials due to its extremely large gravimetric capacity of 18 mass % hydrogen. We focus on an orthorhombic phase observed at ambient conditions and predict its fundamental properties; De-hydrogenation and electronic properties of doped Li1+xB1−xH4 by Li (with 0

Using first principles density functional theory, we predict a monolayer B2Si structure with space group Pmm2 in the present work. This structure is confirmed to be dynamically stable. Based on the plane wave pseudopotential approach, the charge density, electron localization function, density of states, energy band, phonon property and thermal conductivity of Pmm2-B2Si are systematically studied. It is interesting that the sp2 hybridization and coordination bond of Si are found in Pmm2-B2Si, which is the most important factor for its structural stability. The density of states and energy band analysis reveals that Pmm2-B2Si is metallic because of the partial occupied Si 3pz and B 2pz states. Moreover, the acoustic-optical coupling is important for phonon transport in Pmm2-B2Si, and the contribution of optical modes to the lattice thermal conductivity along the [100] and [010] directions is 13% and 12%, respectively. This study gives a fundamental understanding of the structural, electronic and phonon properties in Pmm2-B2Si.

A single component, two-phase lattice Boltzmann model based on the Shan-Chen pseudopotential model is coupled to a continuum-based thermal energy solver. The model is verified using the Stefan problem and Nusselt’s falling film. We then use the model to simulate 2D drop-wise condensation of a saturated vapor on hydrophobic structured surfaces. We report the normalized condensed mass and condensation rate as we vary the spacing between structures, numerical interface thickness, and structure topology. For a non-dimensional spacing of s = 6.4 , a primary droplet engulfs each post after a non-dimensional thermal diffusion time of t ∗ ≈ 1.1 (square), t ∗ ≈ 0.59 (semi-circular), and t ∗ ≈ 2.38 (equilateral). The growth of this thermally resistant primary droplet is fed by coalescing satellite droplets characterized by low heat transfer resistance. These small satellite droplets continuously nucleate, grow and merge into the primary droplet resulting in condensation rates four to seven times greater than the film-wise condensation rate. These small droplets only appear to form when the ratio of numerical interface thickness w to structure length L is sufficiently small ( w / L 0.1 ).

The retarding of metal corrosion due to the effect on economic and safety matters is a challenging research area. The theoretical study could be helpful to understand the mechanism of inhibition and design some new inhibitors. The electronic properties of some pyrimidine derivatives in the gas and aqueous phase were investigated using the m062x/6-311G(3df,3pd) level of theory and the plane wave pseudopotential method and PBE functional were used in the analysis on the Fe(111) surface. The volume and HLG gave the better results for isolated molecule study. Different groups substituted or replaced in thion 2-mercapto pyrimidine (S=Py) structure to enhance its inhibition efficiency. The replacement of Se instead of S revealed the best results in all parameters. The study of inhibitor interaction with the metal surface provides better correlation with the experimental inhibition efficiency and better insight. Keto tautomers represented more efficiency in both gas and solid phase. We predicted that halogenate compounds obey different mechanism to prevent corrosion. Bader analysis indicated that the charge flow occurs from Fe atoms toward inhibitor molecules. As thermodynamic studies confirm that Se=Py is a good inhibitor, the kinetic study of dehydrogenation by CI-NEB method showed lower activation energy for it. So it may be introduced as a new inhibition candidate.

Even though it was put forth 2200 years ago, Archimedes’ principle of buoyancy still has secrets. From the potential energy concept, we confirm that this principle is perfectly applicable for a liquid medium with an arbitrary surface area being either limited or infinitely large. After we quantitatively conceptualize the pseudopotential field of buoyancy, account the pseudopotential energy of buoyancy as part of the total potential energy of a floating object, and immerse uniform cubic toy blocks with various densities in different immersing types into a tank of water with a limited surface, we prove the following general physical criterion: a delicately stable state is the state with the lowest total potential energy which cannot tolerate a subtly higher potential energy. The pseudopotential energy of buoyancy has a significant possibility of being used in obtaining the expected delicate immersion stability of a manmade object on a liquid surface and of being popularized in related hydraulic systems.

The superconducting state parameters (SSPs) such as electron-phonon coupling strength (λ), Coulomb pseudopotential (μ*), transition temperature (TC), effective interaction strength (N0V) and isotopic effect parameter (α) of some binary alloys ( I n 1 − C P b C , I n 1 − C S n C , I n 1 − C T l C , and P b 1 − C T l C ) have been studied theoretically by using pseudopotential theory. Results of SSPs of alloys are found to be in good agreement with other theoretical and available experimental results. Further, applicability of present approach at high pressure has also been justified by carrying out study of SSPs of these alloys as a function of compressed volume using Debye–Gruneisen model. Critical volume at which superconductivity quenches has been predicted by different approaches for all the alloys. The results of critical volume obtained by different approaches are also found to be in excellent agreement with each other. It is important to point out that the presently used pseudopotential is found to be transferable at high pressure because no fitting/refitting of pseudopotential parameters has been done during course of calculation at high pressure.

In this work, manganese was combined with ZIF-67 to form a multi-shell structure, and then the core-shell structure of Co3O4/MnCo2O4.5 as an electrode material was obtained by optimizing the thermal treatment, which perfectly inherited the rhombic dodecahedral shape of the ZIF-67 templates. Benefiting from the composition of core-shell structure and the synergistic effect of bimetallic manganese-cobalt oxides on shell surface, the Co3O4/MnCo2O4.5 reached a specific capacity of 636 F g−1 at a current density of 1 A g−1. Owing to a cycle life of 86% after 5000 charge and discharge cycles, its electrochemical performance had been improved significantly, compared with the Co3O4 acquired by pure ZIF-67 at a specific capacity of 320 F g−1 and a cycle life 79.9%. All of this confirmed the Co3O4/MnCo2O4.5 was an excellent electrode material for the pseudopotential capacitor.

The influence of pressure and temperature on the thermodynamic properties of MgCu intermetallic compound was investigated by quasi-harmonic Debye model approximation. The equation of state (EoS) parameters has performed using plane-wave pseudopotential (PW-PP) approach in the framework of the density functional theory (DFT) and the generalized gradient approximation (GGA) for the exchange-correlation functional. Our results agree well with other data of the literature.The finite temperature thermophysical properties under pressure up to 16 GPa and high temperature up to 800 K, respectively were determined. Our results of the thermophysical properties are also agree very well with other data of the literature, where for example at ambient temperature, the deviation between our obtained value (11.05 Cal mol−1 K−1) of CV, and the theoretical value (11.21 Cal mol−1 K−1) reported in the literature is only around 1.44%. The finite temperature thermophysical properties were found varied monotonically with either temperature or pressure. Compared with other materials previously studied, similar behaviors were observed. Keywords: Thermophysical properties, Quasi-harmonic Debye model, MgCu intermetallic compound, High-pressure

In the classical multiple-relaxation-time (MRT) lattice Boltzmann (LB) method, the transformation matrix is formed by constructing a set of orthogonal basis vectors. In this paper, a theoretical and numerical study is performed to investigate the capability and efficiency of a non-orthogonal MRT-LB model for simulating multiphase flows. First, a three-dimensional non-orthogonal MRT-LB is proposed. A non-orthogonal MRT collision operator is devised based on a set of non-orthogonal basis vectors, through which the transformation matrix and its inverse matrix are considerably simplified as compared with those of an orthogonal MRT collision operator. Furthermore, through the Chapman-Enskog analysis, it is theoretically demonstrated that the three-dimensional non-orthogonal MRT-LB model can correctly recover the macroscopic equations at the Navier-Stokes level in the low Mach number limit. Numerical comparisons between the non-orthogonal MRT-LB model and the usual orthogonal MRT-LB model are made by simulating multiphase flows on the basis of the pseudopotential multiphase LB approach. The numerical results show that, in comparison with the usual orthogonal MRT-LB model, the non-orthogonal MRT-LB model can retain the numerical accuracy while simplifying the implementation.

First principles pseudopotential calculations have been performed to explore the effect of spin-orbit coupling on the electronic, elastic, mechanical, vibrational and electron-phonon interaction properties of noncentrosymmetric BaPtSb crystallizing in the hexagonal SrPtSb-type. This coupling makes only moderate changes to the elastic and mechanical properties but significant changes to the phonon spectrum in the acoustic range. Analysis of the Eliashberg spectral function reveals that these low-frequency phonon modes originate from the vibrations of Pt and Sb atoms and couple strongly to their d and p electronic states at the Fermi level. The spin-orbit coupling has a significant effect on the electron-phonon interaction properties by decreasing the frequencies of some phonon modes and increasing the strength of the most dominant peak of the Eliashberg spectral function. The average electron-phonon coupling increases from 0.617 without spin-orbit coupling to 0.629 with spin-orbit coupling, resulting in the corresponding changes to the superconducting transition temperature from 1.46 to 1.54 K. The latter value of superconducting transition temperature compares very well with its experimental value of 1.64 K.

Recently, Tin Monoxide (SnO) has attained a considerable interest due to its striking electronic, optical, thermoelectric and gas sensing properties in various advanced technological applications. In this study, we focus on the first principles calculations to examine the structural, electronic and optical properties of the pristine, 1S, 2S, and 3S doped SnO. The plane-wave ultra-soft pseudopotential method is used under the GGA-PBE exchange-correlation energy with supercell approach. Bandgap reduces with the increase in the concentration of doping from 0.460 eV to 0.330 eV, 0.064 eV for 1S, 2S respectively and shows metallic behavior for 3S doped SnO. Formation and cohesive energies decrease in order of Sn15S1O16

Four related stannadithiane compounds containing different endocyclic functional groups -including ether (1), diether (2), lactone (3), and spirolactone (4)- were prepared. The conformational landscape has been fully determined for the 8-membered representative (compound 1) resulting in a distorted crown form with the butyl chains adopting an extended conformation. The infrared and Raman spectra of stannadithiane species have been measured and interpreted, aided by quantum chemical calculations and potential energy surface analysis. Special attention has been devoted to the analysis of the vibrational features of the heterocyclic moieties. The characteristic νas(Sn S) and νs(Sn S) stretching modes of the SnS2 endo-cyclic group were clearly observed in the Raman spectra at around 340 and 315 cm−1, respectively. The exo-cyclic ν(Sn C) stretching modes were found near 590 and 565 cm−1 for the antisymmetric and symmetric motions, respectively. Thermal behavior for compounds 2–4 has been determined by thermogravimetric methods.

Hybrid halide perovskites (HHPs) based solar cells have revolutionized the photovoltaic landscape by demonstrating the power conversion efficiencies (PCE) exceeding 23% at a low cost. Through first-principles pseudopotential calculations, we have investigated the structural, electronic and optical properties of Pb-based HHP, CH3NH3PbI3 (MAPbI3) and analyzed the effect of incorporating inorganic Cs+ at methyl ammonium (MA+) cation site in MAPbI3. Our results reveal that 12.5% of Cs-doping slightly enhances the absorption coefficient of MAPbI3, making it a promising candidate for highly efficient perovskite solar cells. This optical absorption is decided by the trade-off between widening of the band gap and increase of DOS in sub-VBM region on Cs-doping. Further, the compositional degradation of MAPbI3 can be prevented with this doping and the solar cells based on it can be used for the longer time.

The pseudopotential plane-wave approach in the framework of the density functional theory, and the density functional perturbation theory with the generalized gradient approach for the exchange-correlation functional has been used to calculate the structural phase stability, elastic constants and thermodynamic properties of boron - arsenide (BAs) compound. The BAs compound transforms from the zincblende phase to rock-salt structure; the phase transition pressure was found to be 141.2 GPa with a volume contraction of around 8.2%. The thermodynamic properties under high pressure and temperature up to 125 GPa and 1200 K respectively were also determined, analyzed and discussed in comparison with other data of the literature. The systematic errors in the static energy were corrected using the bpscal EEC method. Our results agree well with those reported in the literature, where for example, our calculated melting temperature (2116 K) deviates from the theoretical one (2132.83 K) with only 0.8%, and the deviation between our result (1.86) of the Gruneisen parameter and the theoretical one (1.921) is only around 3.2%.

Initial stages of the aluminium nitride epitaxial growth on the gallium nitride (1 1 1)-(2 × 2) surface have been investigated by first-principles total-energy calculations. Studies have been performed within the periodic density functional theory as implemented in the PWscf code of the quantum espresso package. The electron-ion interactions are treated according to the pseudopotential approach. The exchange-correlation energies are treated within the generalized gradient approximation according to Perdew-Burke-Ernzerhof parameterization. First we investigate the Al adsorption on the surface at high symmetry sites with results showing the T4 site as the most stable geometry. The aluminium (Al) coverage varies from ¼ to 1 monolayer. The Al incorporation into the GaN atomic structures occurs by displacing the first layer Ga atoms, with Ga becoming the new adatom to be adsorbed on the surface at high symmetry sites having the T4-2 as the most favorable structure. Surface formation energies (SFE) are calculated; according to results the AlN bilayer formation on top of the surface is the most favorable structure. Moreover the Ga chain on the Al terminated surface may be formed with SFE energy value similar to the Al layer under a Ga layer. Electronic properties have been investigated by calculating the density of states (DOS) and projected density of states (PDOS) of the most favorable structures. At the Fermi level the density of states displays no energy gap indicating that surfaces are metallic.

The structural, mechanical and thermodynamic properties of copper scandium CuSc intermetallic compound under temperature and pressure have been investigated using the plane wave (PW) - pseudopotential (PP) approach in the framework of the density functional theory (DFT). The structural parameters at equilibrium, the elastic moduli, the mechanical stability criteria and the sound velocity are studied in the pressure range 0–12 GPa. In addition, the heat capacity, the Gruneisen parameter, the Debye temperature, the entropy, and the thermal expansion coefficient are studied for temperatures ranging from 0 up to 1000 K. The equilibrium lattice parameter found is around 3.261 A. It is in good agreement with the experimental one of 3.25 A reported in the literature. According to the generalized elastic stability criteria, we predict the occurrence of a phase transition of the B2-type structure at 25.5 GPa. At room temperature and zero-pressure, the isothermal bulk modulus and the Gruneisen parameter found were 80.86 GPa and 2.04 respectively.

The method referred to as G3(MP2)//B3-SBK corresponds to an upgrade of the combination of the G3(MP2)//B3 theory with a compact effective pseudopotential (CEP), originally referred to as G3(MP2)//B3-CEP. The main modifications are related to: a) the replacement of Pople style basis functions by the respective 31G basis sets developed by Stevens, Basch and Krauss, b) re-optimization of the CEP-G3MP2large basis set with respect to some experimental data, c) re-optimization of the higher level correction (HLC) parameters, d) the use of scaled experimental atomization energies of the elements and e) the inclusion of conditions for the calculation of thermochemical properties considering molecules containing Sn and Sb. Evaluations were carried out with properties belonging to the G3/05 training set, i.e. enthalpies of formation, ionization energies, electron affinities, molecular atomization energies and proton affinities. The best combination of adjustments yielded a mean absolute error for all tested properties of 1.43 kcal mol−1. This deviation is essentially equal to that presented by the all-electron G3(MP2)//B3 theory. The inclusion of 40 new molecules containing silicon (3 molecules), germanium (1 molecule), arsenic (4 molecules), tin (26 molecules), and antimony (6 molecules) to the G3/05 training set increased the mean absolute error for all calculated properties to 2.15 kcal mol−1 using the conventional procedure and 1.86 kcal mol−1 by including a scaling of the experimental atomization energies of the elements. Reference experimental properties with lower errors will provide better results for compounds containing Sn and Sb.

Double perovskite-like material Sr2TiMoO6 (STMO) has been obtained by solid state synthesis. Analysis of the morphology by SEM reveals the occurrence of polyhedral grains with octahedral forms in its faces and hexahedron forms in the corners. The electronic structure and thermophysical properties are reported for the first time using the pseudopotential and plane-wave method. Theoretical calculations for different antiferromagnetic configurations showed that the antiferromagnetic spins alignment in planes interspersed along the direction [111] presents the most stable structure. Values of the coefficient of thermal expansion, the Debye temperature, and the Gruneisen parameter show that at low temperatures the specific heat at constant pressure and constant volume has a similar behavior, with a value for the Dulong-Petit limit expected for a triclinic perovskite-type structure. Finally, measures of susceptibility as a function of temperature suggest an antiferromagnetic behavior, with Neel temperature TN = 20.1 K. From the Curie-Weiss adjust, the temperature independent susceptibility was determined to be χo = 0.0038 emu/mol and the effective magnetic moment μ = Peff = μB = 1.30 μB.

Ab-initio calculations based on density functional theory (DFT) and ultrasoft pseudopotentials within both generalized gradient approximation (GGA) proposed by Perdew, Burke and Ernzernof (PBE) and local density approximation (LDA) as parametrised by Perdew and Zunger with the electron-ion interaction treated within Rappe Rabe Joannopoulos (rrkjus) pseudopotential, have been performed to investigate the structural, elastic, mechanical, dynamical and thermodynamic properties of Cadmium dichalcogenides (CdS2, CdSe2 and CdTe2) in pyrite structure. The results of the equilibrium lattice constants and bulk moduli are in agreement with experimental and theoretical studies. Their elastic constants were calculated by fitting the computed stress-strain relationship linearly and their respective mechanical properties were then determined from the three independent elastic constants. The vibrational properties were predicted by calculating the phonon dispersion along high symmetry points using density functional perturbation theory (DFPT). The results obtained revealed that these compounds are ductile systems, they exhibit intra-ionic bonding, and are stable mechanically and dynamically in a pyrite structure. The temperature-dependent behaviours of some thermodynamic properties such as the internal energy, vibrational free energy, entropy and constant volume heat capacity for these compounds were also determined.

Computational calculations based on density functional theory were used to study the structural, electronic, and magnetic properties of the AlC0.0625N0.9375 and AlC0.125N0.875 compounds in the cubic zincblende phase. The calculations were carried out by means of the pseudopotential method, employing the computational Quantum ESPRESSO package. The density of states showed that the compounds has a half-metallic character. The calculated total magnetic moments of AlC0.0625N0.9375 and AlC0.125N0.875 were 1.0 μβ and 2.0 μβ per cell, respectively, the mainly contribution of the total magnetic moment come from 2p-C orbital. The computational calculations predict a Curie temperature of 875 K, which is higher than room temperature. The results suggest that AlN zincblende doped with C is a promising candidate to be a good diluted magnetic semiconductor material.

In the present study, we report the vibrational dynamics of Pd39Ni10Cu30P21 bulk metallic glass in terms of the phonon Eigen frequencies of the localized collective excitations using Show’s optimized model pseudopotential at room temperature. While theoretical effective atom model (EAM) with Wills-Harrison (WH) approach are used for the computation of the interatomic pair potential (PP) and pair correlation function (PCF). The phonon dispersion curves are computed through Hubbard-Beeby (HB) approach. Various elastic and thermodynamic properties have been reported from the elastic limit of the phonon dispersion curves. The screening dependency on the aforesaid properties is studied by adopting different kinds of local field correction functions

We study localized modes (LMs) of the one-dimensional Gross-Pitaevskii/nonlinear Schr\"{o}dinger equation with a harmonic-oscillator (parabolic) confining potential, and a periodically modulated coefficient in front of the cubic term (nonlinear lattice pseudopotential). The equation applies to a cigar-shaped Bose-Einstein condensate loaded in the combination of a magnetic trap and an optical lattice which induces the periodic pseudopotential via the Feshbach resonance. Families of stable LMs in the model feature specific properties which result from the interplay between spatial scales introduced by the parabolic trap and the period of the nonlinear pseudopotential. Asymptotic results on the shapes and stability of LMs are obtained for small-amplitude solutions and in the limit of a rapidly oscillating nonlinear pseudopotential. We show that the presence of the lattice pseudopotential may result in: (i) creation of new LM families which have no counterparts in the case of the uniform nonlinearity; (ii) stabilization of some previously unstable LM species; (iii) evolution of unstable LMs into a pulsating mode trapped in one well of the lattice pseudopotential., Comment: to be published in Commun. Nonlin. Sci. Numer. Simul

The temperature dependence of the band gaps, refractive index, high-frequency and static dielectric constants and optical phonon frequencies in GaAs has been computed by using a pseudopotential approach. Our findings for all features of interest at given temperatures yielded values that agree with those previously reported. The variation of the features being studied here versus temperature showed a monotonic behavior. The transverse optical (TO) and longitudinal optical (LO) phonon frequencies are shifted towards low frequencies when the temperature is raised from 0 to 600 K. The change in the LO-TO splittings by raising temperature reflects the change in the ionicity character of the material under investigation.

The spin-polarized density functional theory as implemented within self-consistent plane wave pseudopotential method is used to investigate the electronic and magnetic properties of ternary alloys Zn1−xCoxSe (for x = 0.125, 0.25 and 0.375) in zinc blende structure. The spin polarised energy band structures reveals that the Zn1-xCoxSe is semiconducting ferromagnet for x = 0.125 and 0.25, it becomes HM ferromagnet for x = 0.375. The band gaps for x = 0.125 and 0.25 configurations are 1.09 and 1.07 eV for spin up channel and 0.65 and 0.39 for spin down channel respectively. The band gaps for x = 0.375 configuration is 0.18 eV for spin up channel. The magnetic moments for x = 0.125 and 0.25 configurations are 3.09 and 3.0 μB and for x = 0.375 configuration is 2.97 μB. The p-d hybridization reduces the local magnetic moment of Co atom from its free space charge value and induced the small atomic magnetic moment on Zn and Se atoms.

One of the K-based binary alloys – K1-XRbX has been studied in the present work. Various thermodynamical properties are computed with the help of pseudopotential theory. The combination of successive elements of the alkali group has been selected for the formation of binary alloys. The well-behaved pseudopotential proposed by Fiolhais et al. is used for the whole calculation. Eight various local field correction functions (namely Hartree (H), Hubbard-Shame (HS), Nagy (N), Vashishtha-Singwi (VS), Taylor (T), Sarkar et al. (S) Ichimaru-Utsumi (IU) and Farid et al .(F) are employed to determine the effect of exchange and correlation on bare ion potential. The present thermodynamical study is based on the successful approach suggested by Gibbs-Bogoliubov (GB). The article includes the calculation of different parts of energy (E), entropy(S) and Helmholtz free energy (EH). The good agreement of the present data with the other theoretical data as well as experimental data is found.

The low cost, highly stable and earth abundant furan-based small molecules have been recognized to be prospective and innovative organic semiconductor materials (OSMs) for optoelectronic applications. In this article, we explore various optoelectronic properties of conjugated isomers containing bifuran (TFFT) and bithiophene (FTTF) by employing the density functional theory (DFT) based ultrasoft pseudopotential approach. Our investigations specify the TFFT as a wide and direct bandgap semiconductor with bandgap value of 2.00 eV. Whereas, the bandgap of FTTF is found to be reduced by 0.239 eV in comparison with TFFT owing towards the effect from p-orbitals of carbon and sulfur atoms present at the center of molecular crystal structure. The reduction in the energy and the density of states (DOS) for the compounds in current study endorsed that bandgap could be tuned to any desired value for optoelectronic applications through derivatives designing. Moreover, the achieved outcomes for optoelectronic parameters like dielectric function, conductivity, refractive index, reflectivity, extinction coefficient and energy loss function validates their suitability to use them in electro-optical devices.