Structural, electronic, mechanical, and thermodynamic properties of UPt3: A first-principles investigation

Theoretically and experimentally, UPt3 has aroused extreme interest due to its exotic properties of heavy fermion superconductivity and spin -fluctuation phenomena. Here, the local density approximation +U (LDA+U) simulations are performed on a heavy fermion superconductor UPt3 to examine its structural, electronic, magnetic, mechanical, and thermodynamic characteristics. By setting the Hubbard U parameter around 2 eV, the calculated lattice parameters agree well with the previous experimental results. The single-crystal elastic constants (Cij) and the polycrystalline elastic moduli (B, G, and E) are reported in detail. The anisotropy is revealed through the anisotropy parameters and the three-dimensional surface architectures of Young's modulus and linear compressibility coefficients. The results show that both ferromagnetic (FM) and antiferromagnetic (AFM) states are mechanically stable. Our calculated phonon spectra demonstrate that both FM and AFM configurations are dynamically stable. The thermodynamic properties of UPt3 for different magnetic states are estimated by the quasi-harmonic approximation (QHA), including free energy, specific heat, entropy, and thermal expansion coefficient. The obtained physical parameters can provide meaningful data for further experimental investigations.