Constant Relaxation Time Approximation Research Articles

Comparative analysis of thermoelectric properties in bulk 2H and monolayer MoS2: a first-principles study at high temperatures

The pursuit of high-efficiency heat-to-electricity conversion is one of the indispensable driving forces toward future renewable energy production. The two-dimensional (2D) transition metal dichalcogenide, such as molybdenum disulfide (MoS2), is at the forefront of research due to its outstanding heat propagation features and potential applications as a thermoelectric material. Using the first-principles density functional theory coupled with the semi-classical Boltzmann transport equation within the constant relaxation time approximation, we present the thermoelectric and energy transport in the bulk 2H and monolayer MoS2 material system. In order to advance the underlying physics, we calculate several crucial transport parameters such as electrical conductivity, electronic thermal conductivity, Seebeck coefficient, and power factor as a function of the reduced chemical potential for different doping types and temperatures, in addition to the electron energy dispersion relation of the material system. Our comprehensive study employs the Shankland interpolation algorithm and the rigid band approximation to attain a high degree of accuracy. This thorough investigation reveals the high Seebeck coefficient of 1534 and 1550 μ V/K at 500 K for the bulk 2H and monolayer MoS2, respectively. Furthermore, the ultrahigh power factor values of 9.21 × 1011 and 3.69 × 1011 Wm −1 K −2 s −1 are shown at 800 K in the bulk 2H and monolayer MoS2, respectively. Based on the power factor results, our in-depth analysis demonstrates that the bulk 2H MoS2, when compared to monolayer MoS2, exhibits great potential as a promising semiconducting thermoelectric material for advanced high-performance energy device applications.

Analysis of semiconductor properties of fabricated graphene materials

Introducing dopant elements into graphene is a crucial process for creating bandgaps, which will have significant importance in developing nanoelectronic devices in the future. In this study, we provide an analysis of the electrical and carrier mobility properties of graphene doped with BN in ratios of 1 %, 3 %, and 5 %, graphene 95 %, ZnO-3 %, and BN2 %, graphene-95 %, Al2O3-3 % and BN-2 %, graphene-95 %, TiO2-3 % and BN-2 % by using a sintering process. Upon analyzing the band structure, it was determined that the mentioned materials demonstrate a bandgap in graphene. The resistivity values for fabricated graphene materials doped with different nanoparticles are estimated using the Source-meter Unit (SMU) at room temperature (25°C), 100°C and 200°C. The conductivity of graphene is 8.93E+07 Ω−1cm−1 and reduced gradually with the doping percentages. The resistivity of graphene is measured at 1.12 E-08 Ω.cmand increases with the doping percentages, and carrier mobility is measured to be 9239 cm2V−1s−1 and gradually reduced with the doping percentages. The temperature-dependent conductivity is determined using electrical conductivity under the constant relaxation time approximation.

Insight on thermodynamic and thermoelectric properties of Ge based perovskites AGeO3 (A = Mg, Cd) for energy harvesting applications: A DFT approach

In this manuscript, transport properties like thermoelectric and thermodynamic properties of AGeO3 (A = Mg, Cd) perovskites have been performed in detail along with effect of chemical potential on various thermoelectric parameters. Furthermore, we present the electronic effects and thermodynamic stability of these materials. The MgGeO3 and CdGeO3 alloys have a gap of 3.368 and 2.555 eV, respectively, making them indirect band gap semiconductors. Furthermore, using a constant relaxation time approximation and semiclassical Boltzmann theory, the thermoelectric (TE) properties of both materials have been studied. The lattice thermal conductivity magnitudes for MGeO3 and CdGeO3 are 7.47 W/mK and 21.55 W/mK, respectively, at 300 K. Power Factor (PF) has been measured at approximately 0 chemical potential, or approximately 14 (1011 W/K2 ms) at 1200 K, 7.5 (1011 W/K2 ms) at 700 K, and 3.5 (1011 W/K2 ms) at 300 K for both MgGeO3 and CdGeO3. At room temperature, the electrical conductivities of MgGeO3 and CdGeO3 were measured to be 1.43 × 1015W/mK and 1.08 × 1015W/mK, respectively. Over a broad temperature range (0–1200 K), the thermodynamic parameters, such as heat capacity, entropy, thermal expansion, and Debye temperature, were also computed and discussed.

Structural stability, optoelectronic, thermoelectric, and elastic characteristics of X2ScBiO6 (X= Mg, Ca, and Ba) double perovskites for energy harvesting: First-principles analysis

Double perovskites have emerged as a potential new material for optoelectronic and thermoelectric applications. We explored structural, electronic, optical, thermoelectric, and elastic properties of double oxides perovskite, X2ScBiO6 (X = Mg, Ca, and Ba) through density functional theory (DFT). The most stable structure, according to the optimized structural parameters, is a cubic Fm3m (225) symmetry with a nonmagnetic (NM) state. We have utilized TB-mBJ to estimate the band structure and density of states. The semiconductor nature is predicted with indirect bandgap values of 1.90 eV, 1.39 eV, and 1.11 eV for Mg2ScBiO6, Ca2ScBiO6, and Ba2ScBiO6, respectively. Notable optical responses such as higher absorption (>105 cm−1) and low reflectivity for X2ScBiO6 suggest appropriate candidates for optoelectronic device applications. The efficient thermoelectric order has been investigated under semiclassical Boltzmann theory and constant relaxation time approximation as implemented in the BoltzTraP (BT) code. Several parameters, such as the Seebeck coefficient, electrical conductivity, thermal conductivity, power factor, and figure of merit, have been calculated. The ductile character of the X2ScBiO6 (X = Mg, Ca, and Ba) compounds is further supported by the elastic properties. Consequently, the results show that the compounds investigated could be good alternatives for thermoelectric and photovoltaic applications.

Validity of the constant relaxation time approximation in topological insulator: Sn-BSTS a case study

Gate-voltage dependent quantum oscillations in topological insulator Sn0.02Bi1.08Sb0.9Te2S (Sn-BSTS) are analyzed on the basis of the Lifshitz−Kosevich theory. The angular dependence of the quantum oscillations and Landau-level fan diagram analysis show that the quantum oscillations originate from topological surface states with the Berry phase of π. Gate-voltage control allows precise control of the Fermi energy, and a very weak energy dependence of the relaxation time τ of the topological surface states is revealed. By a simple algebraic argument using the linear response theory, it is shown that the weak energy dependence of τ validates the constant relaxation time approximation [τE,T=τ0] in the calculation of the Seebeck coefficient S and zTel=σS2T/κel.

Negatively enhanced thermopower near a Van Hove singularity in electron-doped Sr2RuO4

The layered perovskite Sr2RuO4 serves as a model material of the two-dimensional (2D) Fermi liquid but also exhibits various emergent phenomena including the non-Fermi-liquid (NFL) behavior under external perturbations such as uniaxial pressure and chemical substitutions. Here we present the thermoelectric transport of electron-doped system Sr2−yLayRuO4, in which a filling-induced Lifshitz transition occurs at the Van Hove singularity (VHS) point of y≈0.2. We find that the sign of the low-temperature thermopower becomes negative only near the VHS point, where the NFL behavior has been observed in the earlier study. This observation is incompatible with either a numerical calculation within a constant relaxation-time approximation or a toy-model calculation for the 2D Lifshitz transition adopting an elastic carrier scattering. As a promising origin of the observed negatively enhanced thermopower, we propose a skewed NFL state, in which an inelastic scattering with a considerable odd-frequency term plays a crucial role to negatively enhance the thermopower. Published by the American Physical Society 2024

Can Pressure be a Good Strategy for Optimizing Thermoelectric Performance of SnPS3${\rm SnPS}_3$?

AbstractExternal pressure can significantly alter the transport coefficients, power factor, and figure of merit because of its direct influence on the electronic structure, electron–phonon, and phonon–phonon couplings. This study delves into the electronic and thermal transport properties of at external pressures up to 30 GPa using first‐principles calculations and Boltzmann transport theory. The electron–phonon relaxation time is computed within the electron–phonon‐averaged (EPA) approximation, enabling exploration beyond the constant relaxation time approximation. The first‐principles calculations reveal an indirect bandgap of 1.76 (without pressure) and 0.12 eV (30 GPa). The density functional perturbation theory calculations confirm the dynamic stability of at external pressure up to 30 GPa. The electronic transport properties are improved by more than one order of magnitude at 30 GPa, consistent with experimental observations. The Peierls–Boltzmann transport calculations demonstrate the room temperature lattice thermal conductivity of 0.22 (without pressure) and 7.4 (at 30 GPa). The results emanate that exhibits of 0.71 at 900 K at a hole doping of 2 at zero pressure, which decreases with increasing pressure. The findings explore the effect of external pressure on both electronic and thermal transport properties of , warranting further experimental exploration of thermal transport properties at higher pressures.

Investigation of AcXO3 (X = Al, Ga) perovskites for energy harvesting applications: a DFT approach

Full potential linearized augmented plane wave (FP-LAPW) based computational study is presented for AcAlO3 and AcGaO3. Tolerance factor (τG) is 0.93 for AcAlO3 and 0.90 for AcGaO3 which reveal the stability of proposed perovskite oxides in cubic phase. The calculated band structures for both materials reveal the nonmagnetic semiconductive nature with energy band gaps of 3.98 and 2.75 eV for respective Al and Ga based perovskites. Total, and partial density of states (DOS) are computed for meaningful understanding of semiconducting behavior of the proposed perovskites. The partially filled O-2p and Ac-6d states are observed to lie in the vicinity of Fermi level. Furthermore, various parameters of optical spectra have also been computed to study the light matter interaction. Moreover, thermoelectric (TE) properties of both materials have been investigated by using semiclassical Boltzmann theory with constant relaxation time approximation. Calculated figure of merit (ZT) values for AcAlO3 and AcGaO3 are 0.23 and 0.20 at 800 K, respectively. Overall, computational study for titled perovskites indicate that these materials have application in UV sensors, photovoltaic and thermoelectric devices.

Tuning the carrier localization, magnetic and thermoelectric properties of ultrathin ( LaNiO3−δ)1 /( LaAlO3)1 (001) superlattices by oxygen vacancies

Using a combination of density functional theory calculations with an on-site Coulomb repulsion term (DFT+U) and Boltzmann transport theory within the constant relaxation time approximation, we explore the effect of oxygen vacancies on the electronic, magnetic, and thermoelectric properties in ultrathin (LaNiO3−δ)1/(LaAlO3)1(001) superlattices (SLs). For the pristine SL (δ=0), an antiferromagnetic charge-disproportionated (AFM-CD) (d8L̲2)S=0(d8)S=1 phase is stabilized, irrespective of strain. At δ=0.125 and 0.25, the localization of electrons released from the oxygen defects in the NiO2 plane triggers a charge-disproportionation, leading to a ferrimagnetic insulator both at aSrTiO3 (tensile strain) and aLaSrAlO4 (compressive strain). At δ=0.5, an insulating phase emerges with alternating stripes of Ni2+ (high-spin) and Ni2+ (low-spin) and oxygen vacancies ordered along the [110] direction (S-AFM), irrespective of strain. This results in a robust n-type in-plane power factor of 24µW/K2 cm at aSTO and 14µW/K2 cm at aLSAO at 300 K (assuming relaxation time τ=4 fs). Additionally, the pristine and δ = 0.5 SLs are shown to be dynamically stable. This demonstrates the fine tunability of electronic, magnetic, and thermoelectric properties of ultrathin nickelate superlattices by oxygen vacancies. Published by the American Physical Society 2024

Efficient first-principles electronic transport approach to complex band structure materials: the case of n-type Mg3Sb2

We present an efficient method for accurately computing electronic scattering rates and transport properties in materials with complex band structures. Using ab initio simulations, we calculate a limited number of electron–phonon matrix elements, and extract scattering rates for acoustic and optical processes based on deformation potential theory. Polar optical phonon scattering rates are determined using the Fröhlich model, and ionized impurity scattering rates are derived from the Brooks-Herring theory. Subsequently, electronic transport coefficients are computed within the Boltzmann transport theory. We exemplify our approach with n-type Mg3Sb2, a promising thermoelectric material with a challenging large unit cell and low symmetry. Notably, our method attains competitive accuracy, requiring less than 10% of the computational cost compared to state-of-the-art ab initio methods, dropping to 1% for simpler materials. Additionally, our approach provides explicit information on individual scattering processes, offering an alternative that combines efficiency, robustness, and flexibility beyond the commonly employed constant relaxation time approximation with the accuracy of fully first-principles calculations.

Theoretical Investigations of the Structural, Dynamical, Electronic, Magnetic, and Thermoelectric Properties of CoMRhSi (M = Cr, Mn) Quaternary Heusler Alloys

The structural, dynamical, electrical, magnetic, and thermoelectric properties of CoMRhSi (M = Cr, Mn) quaternary Heusler alloys (QHAs) were investigated using density functional theory (DFT). The Y-type-II crystal structure was found to be the most stable configuration for these QHAs. Both CoCrRhSi and CoMnRhSi alloys possess a half-metallic behavior with a 100% spin-polarization as the majority spin channel is metallic. On the other hand, the minority spin channel is semiconducting with narrow indirect band gaps of 0.54 eV and 0.57 eV, respectively, along the Γ−X high symmetry line. In addition, both CoCrRhSi and CoMnRhSi alloys possess a ferromagnetic structure with total magnetic moments of 4 μB, and 5 μB, respectively, which are prominent for spintronics applications. The thermoelectric properties of the subject QHAs were calculated by using Boltzmann transport theory within the constant relaxation time approximation. The lattice thermal conductivities were also evaluated by Slack’s equation. The predicted values of the figure-of-merit (ZT) for CoCrRhSi and CoMnRhSi were found to be 0.84 and 2.04 at 800 K, respectively, making them ideal candidates for thermoelectric applications.

Structural, electronic, optical, and thermoelectric properties of CsPbI3-yBry (y = 0.5, 1.5, 2.5) compounds: First-principle study

BackgroundAmong photovoltaic materials, halide-based perovskites, such as CsPbI3, have been the subject of many research papers due to their suitable and direct bandgap, very good optical properties, and remarkable thermoelectric properties. Enhancing optoelectronic and thermoelectric properties can be achieved by combining halide atoms intelligently. The purpose of this article is to examine the physical properties of Br substitution at different concentrations in CsPbI3 perovskite. MethodsThe structural, electrical, and optical properties of CsPbI3-yBry (y = 0.5, 1.5, 2.5) compounds have been investigated by using the QUANTUM-ESPRESSO/PWSCF computational package which is based on the density functional theory and the pseudo-potential technique. The thermoelectric properties of CsPbI3-yBry perovskites were calculated by solving the Boltzmann transport equations within the constant relaxation time approximation as employed in the BoltzTraP package. Significant findingsThe structural investigation reveals that when the I atom is substituted by Br, the lattice constant decreases, increasing the bulk modulus and stiffness of compounds. The calculated negative formation energy confirmed the thermodynamic stability of CsPbI3-yBry compounds, and the stability improved with an increase in Br concentration. The electronic investigation indicates the semiconductor nature of compounds with a direct band gap, with a slight increase in electronic band gap as Br concentration increases. The noticeable optical absorption coefficient in the visible range of the electromagnetic spectrum, along with high and tunable optical conductivity, confirms the capability of the compounds for use in optoelectronic devices. The positive value of the Seebeck coefficient revealed the p-type semiconducting nature of CsPbI3-yBry perovskites. Lattice thermal conductivity calculation reveals that this quantity is decreased because of the increase in phonon-phonon interaction due to rising temperature. Thermoelectric investigation indicates that a precise mixture of halide I and Br atoms significantly enhances the electrical and thermal conductivity of perovskites. Also, the substitution of halide I atoms by Br can improve the figure of merit (ZT). The maximum value of ZT at room temperature is equal to 0.99, justifying the brilliant thermoelectric properties of the studied compounds.

Mechanical, magneto-electronic and thermoelectric properties of Ba2MgReO6 and Ba2YMoO6 based cubic double perovskites: an ab initio study

We report an analysis of the structural, electronic, mechanical, and thermoelectric properties of oxide double perovskite structures, specifically the compounds Ba2MgReO6 and Ba2YMoO6. Our study employs first-principles density functional theory (DFT) as the investigative methodology. The electronic attributes of the examined compounds are explained by investigating their energy bands, as well as the total and partial density of states. The computational evaluation of the electronic band structure reveals that both compounds exhibit an indirect band gap semiconductor behavior in the spin-down channel, while demonstrating metallic properties in the spin-up channel. The magnetic attributes indicate a ferromagnetic nature, thus categorizing some double perovskite compounds as materials displaying half-metallic ferromagnetism (HM-FM) in addition to some other properties such as metallic and semiconductor in paramagnetic or antiferromagnetic states. The outcomes derived from the analysis of elastic constants confirm the mechanical robustness of the studied double perovskite compounds. Notably, the computed data for bulk modulus (B), shear modulus (G), and Young’s modulus (E) for Ba2MgReO6 surpass those of Ba2YMoO6. The calculated ratio of Bulk to shear modulus (B/G) indicates that both compounds possess ductile characteristics, rendering them suitable for device fabrication. Furthermore, both compounds display outstanding electronic and elastic properties, positioning them as promising contenders for integration within mechanical and spintronic devices. Finally, we investigate into the thermoelectric potential by evaluating parameters such as the Seebeck coefficient, electrical conductivity, thermal conductivity, figure of merit, and power factor. This assessment is conducted using the semiclassical Boltzmann theory and the constant relaxation time approximation, implemented through the BoltzTraP code. The results indicate that the investigated double perovskite oxides hold promise for utilization in thermoelectric applications.

Thermoelectric properties of M[formula omitted]AgAlBr[formula omitted] (M = K, Rb, Cs) double perovskites: A first principles study

Structural, electronic, and transport properties of aluminum-based double halide perovskite M2AgAlBr6 (M = K, Rb, Cs) are here subject of investigation, using first-principles approaches based on density functional theory, as implemented in the plane-wave pseudopotential method. Thermoelectric performance was evaluated by analyzing the results of first-principles band structure calculations and semiclassical Boltzmann theory within the constant relaxation time approximation. The theoretically predicted values for the electronic contribution for the figure of merit are close to 1.0 at room temperature, suggesting that all compounds studied are promising candidates for applications in thermoelectric devices.

The thermal conductivity of ZrCo alloy under doping effect: First principles study

ZrCo alloy is considered to be one of the most promising materials for hydrogen isotope treatment in the International Thermonuclear Experimental Reactor (ITER) due to its significant advantages in dehydrogenation kinetics, thermodynamics, and safety. The heating during the dehydrogenation process, on the other hand, can easily induce H2 to penetrate the surrounding environment, resulting in hydrogen embrittlement and threatening structural safety. The system's temperature regulation is very critical. The electronic thermal conductivity of ZrCo was computed using the BoltzTraP2 program and the constant relaxation time approximation based on density functional theory (DFT). The phonon thermal conductivity is calculated by lattice dynamics using the finite displacement supercell method. Between 300 K and 800 K, the thermal conductivity and electrical conductivity of ZrCo alloy were effectively predicted for the first time. The effects of Ti and V doping on ZrCo alloy thermal conductivity were investigated. The results show that when temperature rises, phonon-electron and phonon-phonon scattering will be enhanced. Resistance and thermal resistance will also rise, while conductivity and thermal conductivity would decrease. The doping of Ti and V elements will reduce the electronic thermal conductivity of the system. Different concentrations of doping bring different degrees of defects, affecting the average electron-phonon free path, and thereby reducing thermal conductivity.

Transport properties of B and N sites vacancy defects graphene/h-BN heterostructures: First-principles study

First-principles calculations based on spin-polarized DFT-D2 approach have been carried out to study the transport properties of graphene/h-BN (G/h-BN) heterostructure (HS), 1 N vacancy defect in G/h-BN (G/h-BN_1 N), nearest neighbour of 1 N & 1B vacancy defects in G/h-BN (G/h-BN_nBN), and alternate zone of 1 N & 1B vacancy defects in G/h-BN (G/h-BN_aBN) materials. Transport properties like electrical conductivity (σ), electronic contribution of thermal conductivity (K), Seebeck coefficient (S) and thermoelectric power factor (P) are estimated through Boltzmann transport equations (BTE) within constant relaxation time approximation (RTA). Quantum ESPRESSO and BoltzTrap packages are used as a computational tool in the calculations. The considered materials are found to be stable van der Waals (vdWs) HS. The σ and K of graphene, h-BN, G/h-BN, G/h-BN_1 N, G/h-BN_nBN and G/h-BN_aBN are found to be increasing monotonically with temperature. The defected materials have slightly less value of σ than that of G/h-BN due to the effect of their effective mass and carrier concentration. At room temperature, K of G/h-BN, G/h-BN_nBN and G/h-BN_aBN retains similar value, while K of G/h-BN_1 N has increased slightly because the increase in Fermi velocity of electrons near Fermi level due to the reduction in effective mass thereby increasing the mean free path. We have analyzed the temperature dependent (constant value of energy) and energy dependent (constant value of temperature) S and P of above-mentioned materials, and found that S and P of defected HS are higher than that of non-defected HS materials due to combine dependence of n, T and m* on the value of S. The estimated S and P values of considered materials are consistent with reported value. Hence, they have budding employment in the thermoelectric devices.

A family of two-dimensional semiconductors with transition metal Kagome lattice, large power factor and ultralow lattice thermal conductivity

Two-dimensional (2D) materials hold promising application potential in the future, so it is worthy to explore new 2D materials with fascinating structures and functionals. Here we predict a series of 15 stable 2D semiconductors, A2B3C4 (A = K, Rb, Cs; B = Ni, Pd, Pt; C = S, Se), using first-principles calculations. The feasibility of mechanical exfoliation from their bulk phases has been confirmed by low cleavage energies. Interestingly, a perfect Kagome lattice formed by transition metal Ni/Pd/Pt atoms have been revealed in these fifteen monolayers. All A2B3C4 monolayers exhibit indirect band features (1.82 eV to 2.76 eV). More encouragingly, and it is theoretically proven, based on constant relaxation time (CRT) approximation, that the A2B3C4 monolayers possess large n-type power factors (1.77 ∼ 2.10 × 103 μWm-1K−2), which is mainly contributed from the loop formed by the conduction band minima in different directions in energy band structure. Furthermore, ultralow lattice thermal conductivity (0.20 Wm-1K−1 to 3.04 Wm-1K−1) has been confirmed in 2D A2B3C4 at room temperature. Finally, the thermoelectric figure of merit (ZT) of A2B3C4 monolayers has been evaluated based on CRT approximation. These interesting findings make A2B3C4 monolayers promising candidates for low-dimensional electronic devices.

First-principles-aided evaluation of the Nernst coefficient beyond the constant relaxation time approximation

The solution of the Boltzmann Transport Equation (BTE) under open voltage conditions and in the presence of simultaneously applied magnetic field and temperature gradient results in the so-called Nernst response of the electrons. The calculation of the Nernst coefficient using first-principles calculations as an extension of the BoltzWann code and under Jones–Zener expansion valid for weak magnetic fields has been the subject of our previous work which provided a general framework for the calculation of the Nernst effect but was not able to capture the experimental results due to the constant relaxation time approximation used. In Contrast to the Seebeck coefficient which is not sensitive to the details of the relaxation times, the Nernst coefficient is proportional to the carrier mobility and hence is greatly affected by the relaxation times. In this work, we focus on the inclusion of the energy-dependent electron–phonon and the electron–impurity relaxation times in our formalism. Using the developed formalism, we successfully reproduced the experimental data of several samples. In this paper, we report our results on Ge, Si, and InSb samples. However, the code is not limited to the reported samples and supports a wide range of materials.

First-Principles Studies on the Physical Properties of the Half Heusler RbNbCd and RbNbZn Compounds: A Promising Material for Thermoelectric Applications

This work focuses on study of the structural, electronic, thermodynamic and thermoelectric properties of RbNbCd and RbNbZn Half Heusler (HH), utilizing a full-potential linearized augmented plane wave (FP-LAPW) approach and the Boltzmann transport equation using a constant relaxation time approximation within the context of density functional theory (DFT) as embedded in the WIEN2k code. The structural analysis employed the generalized gradient approximation (GGA) and considered the Birch Murnaghan equation of state (EOS), which results in the stable phase for RbNbCd and RbNbZn. The positive phonon spectra indicate the dynamical stability of the studied RbNbCd and RbNbZn. The compounds under investigation that have no bandgap are metallic, as evidenced by their electronic properties. Their mechanical and thermal stability as well as their anisotropic and ductile character are confirmed by the various elastic and thermodynamic parameters. The lattice thermal conductivity has been calculated. This thorough analysis demonstrates the applicability of the studied RbNbCd and RbNbZn for thermoelectric applications.

Ab initio calculation of thermoelectric properties in 3d ferromagnets based on spin-dependent electron–phonon coupling

Crossed magneto-thermo-electric coefficients are central to novel sensors and spin(calori)tronic devices. Within the framework of Boltzmann’s transport theory, we calculate the resistivity and Seebeck coefficients of the most common 3d ferromagnetic metals: Fe, Co, and Ni. We use a fully first-principles variational approach, explicitly taking electron-phonon scattering into account. The electronic band structures, phonon dispersion curves, phonon linewidths, and transport spectral functions are reported, comparing with experimental data. Successive levels of approximation are discussed: constant relaxation time approximation, scattering for a non-magnetic configuration, then spin polarized calculations with and without spin–orbit coupling (enabling spin-flips). Spin polarization and explicit electron–phonon coupling are found to be necessary to reach a correct qualitative picture: the effect of spin flipping is substantial for resistivity and very delicate for the Seebeck coefficient. The spin-dependent Seebeck effect is also predicted.