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In this work, the role of spin‐orbit coupling (SOC) in the physical properties of TlBi2${\rm TlBi}_2$ is reported. These electronic calculations reveal that the heavy elements Tl and Bi promote strong spin‐orbit coupling, lifting some of the degeneracies at the high‐symmetry points. The presence of SOC causes significant decreases in both elastic constants and elastic moduli, which in turn improve the compatibility of the calculated Debye temperature (ΘD$\Theta _D$ = 80 K) with the recent experimental data of 83 K. Furthermore, our quasi‐static harmonic approximation calculation, like this elastic constant calculation, confirms that taking SOC into account improves agreement with the experiment by decreasing value of Debye temperature from 95 to 85 K. Activating the SOC causes significant modifications in the phonon spectrum and the density of phonon states, as well as in the Eliashberg spectral function. As a result of these modifications, the electron–phonon coupling parameter (λ$\lambda$) increases from 1.178 to 1.259, by ≈7%$\approx 7\%$. The calculated values of λ$\lambda$ both with and without SOC imply that TlBi2${\rm TlBi}_2$ can be treated as phonon‐mediated superconductor with strong coupling. The SOC‐induced increase in λ$\lambda$ brings the superconducting transition temperature of TlBi2${\rm TlBi}_2$ from 6.076 to 6.211 K, which is almost equal to the recent experimental value of 6.2 K. [ABSTRACT FROM AUTHOR]

Ab initio pseudopotential calculations have made for the structural, electronic, elastic, mechanical, and electron–phonon interaction properties of molybdenum borocarbide ( Mo 2 BC) and niobium boronitride ( Nb 2 BN) superconductors. Analysis of the structural and electronic properties reveals that the nature of bonding in both these compounds is a combination of covalent, ionic, and metallic. The near-Fermi electronic states in both compounds are occupied by the d states of transition metal atoms. The electronic density of states at the Fermi level in Mo 2 BC is significantly higher than that in Nb 2 BN. Lattice dynamical calculations verify their dynamical stability in the base-centered orthorhombic Mo 2 BC-type crystal structure. We find that the total electron–phonon coupling constant is equal to 0.745 for Mo 2 BC and 0.539 for Nb 2 BN. The calculated superconducting transition temperature of 7.41 K for Mo 2 BC and 3.50 K for Nb 2 BN is comparable with their experimental values of 7.2 and 4.4 K, respectively. [ABSTRACT FROM AUTHOR]

We examine the effects of interface density, quality, and period size on the lattice thermal conductivity of nanocomposite materials within the framework of a recently developed extended modified effective medium approach. A density functional theory and Boltzmann equation based semi-ab initio approach is used to calculate the constituent thermal conductivities, and the effective thermal boundary conductance is computed by modeling interface roughness based on a realistic combination of acoustic mismatch and diffuse mismatch contributions, for systems with anisotropic (directionally dependent) and isotropic thermal conductivities. Results obtained for Si/Ge and MoS 2 / WS 2 systems indicate that the effective cross-planar thermal conductivity of planar superlattice systems is closely related to the thermal boundary resistance of the system for small superlattice periods, whereas in nanodot superlattices, the effective thermal conductivity for small particles is primarily regulated through the effective scattering lengths used in the calculation of the insert and matrix conductivities. [ABSTRACT FROM AUTHOR]