Electronic structure effects of the anharmonic modes of FeV at high pressure.

Classical molecular dynamics methods can describe accurately a broad set of many-atom systems. Although more economic, the results given by this framework lack the precision that density functional theory (DFT) is capable of. We analyze the dynamical stability of the B2 phase of the equiatomic iron-vanadium (FeV) alloy using DFT to verify and further explain recent results obtained by our group that show the behavior of the transverse acoustic (TA) M5 phonon modes and several others to be highly anharmonic and sensitive to temperature. The degenerate TA M5 modes in particular are destabilized by pressure but stabilized by temperature. The band structure, the electronic density of states (eDOS) and the phonon dispersion relations at 0 K and at finite atomic displacements corresponding to 300 K temperature were computed. The finite-temperature phonon dispersion relations are calculated fitting the effective force constants model with the Born-von-Karman model up to the fifth nearest neighbors. The magnetization disappears with temperature, and we investigate how the charge transfer between orbitals might be responsible for the anharmonic behavior of the phonons.