Spin-orbit Coupling Corrections Research Articles

Effect of Pyrrolidinedithiocarbamate Ligand on the Luminescence Properties of Heteroligand Samarium and Europium Complexes: Experimental and Theoretical Study.

The photophysical properties of two isostructural heteroligand lanthanide complexes of general formula Ln(pdtc)3(phen) (pdtc = pyrrolidinedithiocarbamate anion, phen = 1,10-phenanthroline), Ln = Sm3+ (1), Eu3+ (2)) were studied in solid state and dichloromethane (DCM) solution. The two lanthanide complexes were investigated by experimental techniques for structural (single-crystal X-ray diffraction analysis of 1, powder XRD, TG-DTA) and spectroscopic [electron paramagnetic resonance (EPR), infrared (IR), ultraviolet-visible (UV-vis), photoluminescence (PL)] characterization. DFT/TDDFT/ωB97xD and multireference SA-CASSCF/NEVPT2 calculations with perturbative spin-orbit coupling corrections were applied to construct the Jablonski energy diagrams and to discuss the excited state energy transfer mechanism with competing excited state processes and possible sensitized mechanism of metal-centered emission. The first excited state (S1) involved in the excited state energy transfer L(antenna)-to-Ln was predicted to have interligand (pdtc-to-phen) charge transfer character in contrast to the previously predicted ligand-to-metal charge transfer character. The theoretical consideration showed similar relaxation paths and luminescence quenching channels and appropriate Donor*(phen)-Acceptor*(Ln3+) energy gap for 1 and 2. The experimental measurements in the solid state, however, showed efficient luminescence and good ability to convert UV to visible light only for the Sm(pdtc)3(phen) complex. The minor emission of 2 was explained by partial reduction of Eu3+, confirmed by EPR and calculated electron density distribution data.

Automated workflow for analyzing thermodynamic stability in polymorphic perovskite alloys

In this first-principles investigation, we explore the polymorphic features of pseudo-cubic alloys, focusing on the impact of mixing organic and inorganic cations on their structural and electronic properties, configurational disorder, and thermodynamic stability. Employing an automated cluster expansion within the generalized quasichemical approximation (GQCA), our results reveal how the effective radius of the organic cation (rMA = 2.15 Å, rFA = 2.53 Å) and its dipole moment (μMA = 2.15 D, μFA = 0.25 D), influences Glazer’s rotations in the A1−xCsxPbI3 (A = MA, FA) sublattice, with MA-based alloy presenting a higher critical temperature (527 K) and being stable for x > 0.60 above 200 K, while its FA analog has a lower critical temperature (427.7 K) and is stable for x < 0.15 above 100 K. Additionally, polymorphic motifs magnify relativistic effects, impacting the thermodynamic behavior of the systems. Our methodology leverages the SimStack framework, an automated scientific workflow that enables the nuanced modeling of polymorphic alloys. This structured approach allows for comprehensive calculations of thermodynamic properties, phase diagrams, optoelectronic insights, and power conversion efficiencies while meticulously incorporating crucial relativistic effects like spin-orbit coupling (SOC) and quasi-particle corrections. Our findings advocate for the rational design of thermodynamically stable compositions in solar cell applications by calculating power conversion efficiencies using a spectroscopic limited maximum efficiency model, from which we obtained high efficiencies of about 28% (31–32%) for MA1−xCsxPbI3 with 0.50 < x < 1.00 (FA1−xCsxPbI3 with 0.0 < x < 0.20) as thermodynamically stable compositions at room temperature. The workflow’s significance is highlighted by a Colab-based notebook, which facilitates the analysis of raw data output, allowing users to delve into the physics of these complex systems. Our work underscores the pivotal role of composition and polymorphic degrees in determining the stability and optoelectronic properties of MHP alloys. It demonstrates the effectiveness of the SimStack workflow in advancing our understanding of these materials.

Effect of the spin-orbit coupling and Hubbard corrections in predicting the electronic and magnetic properties of vacancy-ordered double perovskites A2WCl6 (A = Rb and Cs)

The structural, elastic, electronic, and magnetic properties of the vacancy ordered double perovskite compounds A2WCl6 (A = Rb, Cs) have been investigated within the full-potential linearized augmented plane waves (FP-LAPW) method. The structural properties in the cubic phase were examined and are consistent with the available experimental results. The materials are more stable in the ferromagnetic phase. The mechanical, dynamical and the thermodynamical stability have also been verified. The electronic and magnetic properties were first calculated by GGA-WC approximation, the studied materials are found to be half-metallic. Including Hubbard correction (U), the W-d states move towards higher energy enlarging the band gap in the spin-down channel. The spin–orbit coupling (SOC) was added to GGA-WC+U which reveal that these compounds behave as semiconductors in both spin channels. The density of states showed that the valence band is mainly characterized by the W-d together with Cl-p states while the conduction band is dominated by W-d and (Cs/Rb)-d states. The calculated properties present semiconducting ferromagnetic nature that is considered as necessary factor in spintronics applications.

Optoelectronic Readout of Single Er Adatom's Electronic States Adsorbed on the Si(100) Surface at Low Temperature (9 K).

Integrating nanoscale optoelectronic functions is vital for applications such as optical emitters, detectors, and quantum information. Lanthanide atoms show great potential in this endeavor due to their intrinsic transitions. Here, we investigate Er adatoms on Si(100)-2×1 at 9 K using a scanning tunneling microscope (STM) coupled to a tunable laser. Er adatoms display two main adsorption configurations that are optically excited between 800 and 1200 nm while the STM reads the resulting photocurrents. Our spectroscopic method reveals that various photocurrent signals stem from the bare silicon surface or Er adatoms. Additional photocurrent peaks appear as the signature of the Er adatom relaxation, triggering efficient dissociation of nearby trapped excitons. Calculations using density functional theory with spin-orbit coupling correction highlight the origin of the observed photocurrent peaks as specific 4f→4f or 4f→5d transitions. This spectroscopic technique can facilitate optoelectronic analysis of atomic and molecular assemblies by offering insight into their intrinsic quantum properties.

DFT2kp: Effective kp models from ab-initio data

The k\cdot pk⋅p method, combined with group theory, is an efficient approach to obtain the low energy effective Hamiltonians of crystalline materials. Although the Hamiltonian coefficients are written as matrix elements of the generalized momentum operator \pi= p+ p_{SOC}π=p+pSOC (including spin-orbit coupling corrections), their numerical values must be determined from outside sources, such as experiments or ab initio methods. Here, we develop a code to explicitly calculate the Kane (linear in crystal momentum) and Luttinger (quadratic in crystal momentum) parameters of k\cdot pk⋅p effective Hamiltonians directly from ab initio wavefunctions provided by Quantum ESPRESSO. Additionally, the code analyzes the symmetry transformations of the wavefunctions to optimize the final Hamiltonian. This is an optional step in the code, where it numerically finds the unitary transformation UU that rotates the basis towards an optimal symmetry-adapted representation informed by the user. Throughout the paper, we present the methodology in detail and illustrate the capabilities of the code applying it to a selection of relevant materials. Particularly, we show a “hands-on” example of how to run the code for graphene (with and without spin-orbit coupling). The code is open source and available at https://gitlab.com/dft2kp/dft2kp.

Codebase release 0.0 for DFT2kp

The k\cdot pk⋅p method, combined with group theory, is an efficient approach to obtain the low energy effective Hamiltonians of crystalline materials. Although the Hamiltonian coefficients are written as matrix elements of the generalized momentum operator \pi= p+ p_{SOC}π=p+pSOC (including spin-orbit coupling corrections), their numerical values must be determined from outside sources, such as experiments or ab initio methods. Here, we develop a code to explicitly calculate the Kane (linear in crystal momentum) and Luttinger (quadratic in crystal momentum) parameters of k\cdot pk⋅p effective Hamiltonians directly from ab initio wavefunctions provided by Quantum ESPRESSO. Additionally, the code analyzes the symmetry transformations of the wavefunctions to optimize the final Hamiltonian. This is an optional step in the code, where it numerically finds the unitary transformation UU that rotates the basis towards an optimal symmetry-adapted representation informed by the user. Throughout the paper, we present the methodology in detail and illustrate the capabilities of the code applying it to a selection of relevant materials. Particularly, we show a “hands-on” example of how to run the code for graphene (with and without spin-orbit coupling). The code is open source and available at https://gitlab.com/dft2kp/dft2kp.

Prediction of structural, elastic, electronic and thermoelectric properties of the Rb3CuO and Rb3AgO anti-perovskites

The Structural, elastic and electronic and thermoelectric properties of anti-perovskites Rb3AgO and Rb3CuO compounds have been investigated using the full potential linearised augmented plane waves (FP-LAPW) method based on the density functional theory (DFT) implemented in the wien2k code. The analysis of the structural and elastic properties of Rb3AgO and Rb3CuO antiperovskites compounds were performed with mean of the generalized gradient potential approximation developed by Perdew–Burke–Ernzerhof (GGA-PBE) while the electronic and thermoelectric properties have been calculated using the GGA-PBE + TBmBJ approximation. In all calculations the spin-orbit coupling correction is tested which revealed it insignificant effect on the electronic properties and the related properties. These materials are found to be indirect narrow band gap semiconductors and exhibit good thermoelectric performance with a figure of merit ZTe ∼1. On the other hand, investigation of the phonon dispersion and the formation energy indicate the possible synthesize of these materials. In the absence of other theoretical and experimental results for Rb3AgO and Rb3CuO, this work is considered as a first prediction.

Structural, electronic and optical properties of the YVO4:Eu3+ red phosphor

The structural, electronic and optical properties of the YVO4:Eu3+ compound have been discussed in terms of the results of the first-principles calculations on the density functional theory level. The emphasis has been given to the analysis of the Eu contribution to these properties. The calculations have been performed in a frame of the mBJ + SO + U approach, i.e. applying modified Becke-Johnson (mBJ) potential for exchange-correlation effects, spin-orbit (SO) coupling, and Hubbard correction U for the Eu 4f-shell treatment. The electronic structure of the pure YVO4 is found to be similar to previously published ones, with the O 2p- and the V 3d-states dominating the valence and the conduction band respectively, but with the improved bandgap description (3.7 eV compared to the experimentally determined 3.8 eV). In the case of the YVO4:Eu3+, different U values have been tested in order to obtain the best agreement between calculated and experimental optical absorption (OA) spectra. The value of U = 2.5 eV fulfilled this condition. The bandgap is found to be 3.6 eV, independently of the applied U value. The basic features of the electronic structure did not change with respect to the pure compound. The Eu spin-up 4f-states (accommodating 6 electrons) are found to be spread out within the valence band, with a very narrow empty band (accommodating 1 spin-up electron) localized inside the bandgap, around 2 eV measured from the valence band top. A rich structure of various sharp peaks in the energy interval 2–3 eV of the OA spectrum, observed experimentally, has been reproduced and explained in terms of electron transitions to the empty Eu 4f band inside the gap. The calculated OA spectrum is found to be very anisotropic, with dominating absorption of light polarized parallel to the tetragonal c-axis.

Theoretical Comparison Study of Iodine and Astatine Adsorption on Au(111) Surface

Gold nanoparticles (AuNPs) are used in many applications including in cancer therapy. One way to improve the quality of treatment is to design AuNPs to provide optimum adsorption to the radionuclides being employed. Therefore, we have to first understand the mechanism and quantify the strength of such adsorption process. This study looks at the adsorption characteristics of iodine and astatine on gold nanoparticles, specifically the (111) surface to learn more about adsorption of such heavy elements on Au surfaces. Both iodine and astatine are found to be able to bond with Au(111) via covalent bonding most stably on the face-centered cubic (fcc) site. We also found that the adsorption strength of iodine and astatine on gold are comparable, and that spin orbit coupling correction does not significantly affect the adsorption energies.

DFT + U study of electronic and optical properties of Cu3TMTe4: TM = V, Nb, Ta with incorporation of SOC

Density Functional Theory (DFT) calculations of structural, electronic and optical properties of copper sulvanite compounds (Cu3TMTe4; TM = V, Nb, Ta) was performed by incorporating spin orbit coupling (SOC) and Hubbard (U) correction for Cu-d orbitals. Analysis of the result shows that SOC effect slightly reduces the electronic band gap of each of the copper sulvanite compounds by 0.10–0.12 eV respectively. Furthermore SOC splitting of bands at R symmetry point of the valence band (VB) with split off energy Δso = 0.33, 0.34 and 0.34 eV for V, Nb and Ta family of compounds are respectively observed. Moreover the optical properties fulfill certain condition for promising solar photovoltaic (PV) absorber with minute observed SOC effect. Theoretical prediction provided with DFT + U calculation along with the incorporation of SOC may provide valuable data for development of nanodevices.

High-level ab initio mapping of the multiple H-abstraction pathways of the OH + glycine reaction.

We perform a systematic search in the transition-state (TS) and product-channel complex (MIN) regions of the multi-channel OH + glycine → H2O + H2N-CH-COOH (CH)/HN-CH2-COOH (NH)/H2N-CH2-COO (COOH) reactions. Geometry optimizations reveal {7, 3, 3} CH-TS, {2, 2, 2} CH-MIN, {17, 10, 5} NH-TS, {35, 19, 19} NH-MIN, and {6, 5, 5} COOH-TS conformers at the {MP2/3-21G, MP2/aug-cc-pVDZ, CCSD(T)-F12b/aug-cc-pVDZ} levels of theory as well as 2 additional CH-TSs based on chemical intuition. The benchmark relative energies of the TS, MIN, and product conformers are obtained by considering basis set effects up to aug-cc-pVQZ using the explicitly-correlated CCSD(T)-F12b method, post-(T) correlation up to CCSDT(Q), core correlation, scalar relativistic effects, spin-orbit coupling, and zero-point energy corrections. All the CH [ΔEe(ΔH0) = -38.54(-38.61) kcal mol-1], NH [ΔEe(ΔH0) = -16.72(-17.98) kcal mol-1], and COOH [ΔEe = -4.98 kcal mol-1] reactions are exothermic and proceed via shallow, usually negative, classical(adiabatic) barriers of -0.37(-0.95), -1.91(-2.48), and 1.02(-0.57) kcal mol-1, respectively. In the entrance channel MRCI/aug-cc-pVTZ computations reveal several complexes with reactive(non-reactive) arrangements and binding energies of 1.0, 1.6, 3.3, (5.2 and 5.9) kcal mol-1, stabilized by CH⋯OH, NH⋯OH, COOH⋯OH, (OH⋯OC and OH⋯N) hydrogen bonds, respectively.

The density functional theory study of substitution effect in antiferromagnetic USn0.5Sb1.5

The electronic structure of antiferromagnetic (AF) USn0.5Sb1.5 crystallizing in the tetragonal Cu2Sb-type structure is investigated by means of ab-initio calculations using the full-potential linearized augmented plane wave method (FP-LAPW) method. Using Local-spin density approximation (LSDA) with the inclusion of spin-orbit coupling (LSDA ​+ ​SO) and Hubbard corrections (LSDA ​+ ​SO ​+ ​U-J) in the calculations, the most stable magnetic ground with an ordered magnetic moment of ∼ 1.7 μB is predicted for the system. Meaningful changes in the lattice parameters, magnetic moments, and magnetic ground state instabilities of USn0.5Sb1.5 are discussed in terms of effects brought by the Coulomb interaction, and the Hund coupling. The calculated electronic properties involving Densities of States (DOS), Electronic Band Structures (EBS), Electron Localization Functions (ELF), and Fermi Surfaces (FS) are presented and compared to those of the parent USb2 compound. The electronic properties, particularly FS and ELF, are found to be strongly modified as a result of the Sn-substitution. The reformation of anisotropy in the FS and ELF upon changing magnetic states (paramagnetic → antiferromagnetic) is examined.

Benchmark Ab Initio Characterization of the Abstraction and Substitution Pathways of the Cl + CH3CN Reaction.

We investigate the reaction pathways of the Cl + CH3CN system: hydrogen abstraction, methyl substitution, hydrogen substitution, and cyanide substitution, leading to HCl + CH2CN, ClCN/CNCl + CH3, ClCH2CN + H, and CH3Cl + CN, respectively. Hydrogen abstraction is exothermic and has a low barrier, whereas the other channels are endothermic with high barriers. The latter two can proceed via a Walden inversion or front-side attack mechanism, and the front-side attack barriers are always higher. The C-side methyl substitution has a lower barrier and also a lower endothermicity than the N-side reaction. The computations utilize an accurate composite ab initio approach and the explicitly correlated CCSD(T)-F12b method. The benchmark classical and vibrationally adiabatic energies of the stationary points are determined with the most accurate CCSD(T)-F12b/aug-cc-pVQZ energies adding further contributions of the post-(T) and core correlation, scalar relativistic effects, spin–orbit coupling, and zero-point energy corrections. These contributions are found to be non-negligible to reach subchemical accuracy.

Role of post-CCSD(T) corrections in predicting the energetics and kinetics of the OH˙ + O3 reaction.

The present work investigates the OH˙ +O3 reaction by means of chemical kinetics and quantum chemical calculations. To estimate the reaction barrier height and reaction energy, we have included various corrections, like zero point energy corrections, contribution from full triple excitations and partial quadratic excitations at the coupled-cluster level, core corrections, diagonal Born-Oppenheimer corrections and spin-orbit coupling corrections. The reaction barrier and reaction energy were estimated to be 1.64 kcal mol-1 and -39.97 kcal mol-1, respectively, which are in good agreement with the experimental results. Using this barrier height, we have estimated the rate constants using transition state theory augmented with zero curvature tunneling (TST/ZCT) in the temperature range of 220-450 K and the thus obtained rate constants were compared with available experimental results.

Carbon doping effect on the optoelectronic properties of the KNO3 material

In this work, we present studies based on the two methods density functional theory (DFT) and time-dependent density functional theory (TDDFT) to illustrate the optoelectronic properties of the pure and doped KNO3. In fact, the used DFT method is carried out under the Quantum Espresso package. Moreover, our investigations are performed on the basis of the generalized-gradient approximation of Perdew–Burke–Eruzerhof without and with the spin orbit coupling (SOC) correction. The ab-initio calculations of the studied compound have been performed while relying to the DFT, using the Quantum Espresso code. The obtained results and calculations are simulated under norm-conserving pseudo-potentials for calculations without SOC calculations and fully-relativistic ultra-soft pseudo-potentials for SOC calculations. The width of the Gaussian smearing was set to 0.1 eV. It has been found that the main result of the doping effect is to decrease the energy band gap of the KNO3. While, the gap nature is still direct in the Γ point in both pure and doped cases.

First-principles predictions of Hall and drift mobilities in semiconductors

Significant progress on parameter-free calculations of carrier mobilities in real materials has been made during the past decade; however, the role of various approximations remains unclear and a unified methodology is lacking. Here, we present and analyse a comprehensive and efficient approach to compute the intrinsic, phonon-limited drift and Hall carrier mobilities of semiconductors, within the framework of the first-principles Boltzmann transport equation. The methodology exploits a novel approach for estimating quadrupole tensors and including them in the electron-phonon interactions, and capitalises on a rigorous and efficient procedure for numerical convergence. The accuracy reached in this work allows to assess common approximations, including the role of exchange and correlation functionals, spin-orbit coupling, pseudopotentials, Wannier interpolation, Brillouin-zone sampling, dipole and quadrupole corrections, and the relaxation-time approximation. A detailed analysis is showcased on ten prototypical semiconductors, namely diamond, silicon, GaAs, 3C-SiC, AlP, GaP, c-BN, AlAs, AlSb, and SrO. By comparing this extensive dataset with available experimental data, we explore the intrinsic nature of phonon-limited carrier transport and magnetotransport phenomena in these compounds. We find that the most accurate calculations predict Hall mobilities up to a factor of two larger than experimental data; this could point to promising experimental improvements in the samples quality, or to the limitations of density-function theory in predicting the carrier effective masses and overscreening the electron-phonon matrix elements. By setting tight standards for reliability and reproducibility, the present work aims to facilitate validation and verification of data and software towards predictive calculations of transport phenomena in semiconductors.

Computational study of the structural, elastic, electronic and thermoelectric properties of the orthorhombic perovskite CaIrO3 compound

The first principles analysis of structural, elastic, electronic and thermoelectric properties of Calcium Iridium perovskite CaIrO3 compound have been reported. We made our calculations within the full-potential linearized augmented plane wave (FP-LAPW) method, based on Density Functional Theory (DFT) within GGA-PBEsol and GGA-PBEsol with the co-operative effect of spin–orbit coupling correction for exchange-correlation potentials. The calculated structural properties, namely the equilibrium lattice parameters and cell volume, are in good agreement with available experimental data. All single crystal elastic constants are computed, from which values of shear, bulk, Young's modulus and Poisson's ratio for CaIrO3 are calculated using Voigt and Hill approximations. It's found that CaIrO3 compound is ductile and has greater anisotropy in (100) plane. The electronic transport properties at room temperature are obtained via Boltzman transport theory, the Hall coefficient exhibited a sign change as a function of temperature, indicates that the perovskite CaIrO3 is semimetal. Therefore, CaIrO3 is n-type material. The electronic band structure calculations indicate the presence of Dirac point around the Fermi level between the directions (Y-Γ).

Spin-Orbit Coupling Effect on the Electrophilicity Index, Chemical Potential, Hardness and Softness of Neutral Gold Clusters: A Relativistic Ab-initio Study

Electrophilicity index (𝜔) is related to the energy lowering associated with a maximum amount of electron flow between a donor and an acceptor and possesses adequate information regarding structure, stability, reactivity and interactions. Chemical potential (μ) measures charge transfer from a system to another having a lower value of μ, while chemical hardness (η) is a measure of characterizing relative stability of clusters. The main purpose of the present research work is to examine the Spin-Orbit Coupling (SOC) effect on the behavior of the electrophilicity index, chemical potential, hardness and softness of neutral gold clusters Aun (n=2-6). Using the second-order Douglas-Kroll-Hess Hamiltonian, geometries are optimized at the DKH2-B3P86/DZP-DKH level of theory. Spin-orbit coupling energies are computed using the fourth-order Douglas-Kroll-Hess Hamiltonian, generalized Hartree-Fock method and all-electron relativistic double-ζ level basis set. Then, spin-orbit coupling (SOC) corrections to the electrophilicity index, chemical potential, hardness and softness are calculated. It is revealed that spin-orbit correction to the vertical chemical hardness has important effect on Au3 and Au6, i.e. SOC decreases (increases) the hardness of gold trimer (hexamer). Due to the relationship between hardness and softness, σ = , inclusion of spin-orbit coupling increases (decreases) the softness of Au3 (Au6) and thus destabilizes (stabilizes) it. Spin-orbit coupling (SOC) also has more important effect on the chemical potential of Au3 by decreasing its value. It is found that spin-orbit coupling has considerable effect on the electrophilicity index of gold trimer and greatly increases its value. Furthermore, SOC increases the maximal charge acceptance of Au3 more and thus destabilizes it more. As a result, spin-orbit coupling effect appears to be important in calculating the electrophilicity index of the gold trimer. Doi: 10.28991/HIJ-2021-02-01-05 Full Text: PDF

How the Ancillary Ligand X Drives the Redox Properties of Biscyclopentadienyl Pentavalent Uranium Cp2U(═N-Ar)X Complexes.

Relativistic zero order regular approximation (ZORA) density functional theory computations, coupled with the conductor-like screening model for solvation effects, are used to investigate the redox properties of a series of biscyclopentadienyl pentavalent uranium(V) complexes Cp2U(═N-Ar)X (Ar = 2,6-Me2-C6H3; X = OTf, C6F5, SPh, C═CPh, NPh2, Ph, Me, OPh, N(TMS)2, N═CPh2). Regarding the UV/UIV and UVI/UV couple systems, a linear correlation (R2 ∼ 0.99) is obtained at the ZORA/BP86/TZP level, between the calculated ionization energies and the measured experimental E1/2 half-wave oxidation potentials (UVI/UV) and between the electron affinities and the reduction potentials E1/2 (UV/UIV). The study brings to light the importance of solvation effects that are needed in order to achieve a good agreement between the theory and experiment. Introducing spin-orbit coupling corrections slightly improves this agreement. Both the singly occupied molecular orbital and the lowest unoccupied molecular orbital of the neutral UV complexes exhibit a majority 5f orbital character. The frontier molecular orbitals show a substantial ancillary ligand X σ and/or π character that drives the redox properties. Moreover, our investigations allow estimating the redox potentials of the X = Ph, X = C6F5, and N(TMS)2 UV complexes for which no experimental electrochemical data exist.

Band gaps of the solar perovskites photovoltaic CsXCl3 (X=Sn, Pb or Ge)

In this work, we are studying structural and electronic properties of the solar perovskites photovoltaic CsXCl3 (X = Sn, Pb or Ge) using the ab-initio calculations under the Quantum Espresso package. The total and partial density of states (DOSs) have been elaborated and discussed for each material: CsSnCl3, CsPbCl3 and CsGeCl3. On the other hand, the band structure of each one of these materials has been established. It is found that these materials exhibit a non-magnetic and semi-conductor behavior. The dependency of the band gap of the solar perovskites photovoltaic CsXCl3 (X = Sn, Pb or Ge) is illustrated as a function of the lattice parameter ‘a’ (Å). It is found that when increasing the lattice parameter the band gap increases for all the materials: CsSnCl3, CsPbCl3 and CsGeCl3. In addition, for a fixed value of the lattice parameter ‘a’ the band gap increases when we move from one material to another: CsSnCl3, CsGeCl3 and CsPbCl3, respectively.To complete this study, we have inspected the effect of the spin orbit coupling (SOC) correction on the band gap energy of the different solar perovskite materials CsXCl3 (X = Sn, Pb or Ge), when using the optimized lattice parameter values. Our results revealed that the (SOC) effect is to decrease the band gap energy values of the three studied solar perovskite materials.