Combined Molecular Dynamics-Spin Dynamics Simulation of $\alpha$-Iron in an External Magnetic Field

Using an atomistic model that treats both translational and spin degrees of freedom, combined molecular and spin dynamics simulations have been performed to study dynamic properties of $\alpha$-iron. Atomic interactions are described by an empirical many-body potential\footnote{Dudarev S L, Derlet P M 2005 \textit{J. Phys.: Cond. Matter} \textbf{17} 7097} while spin-spin interactions are handled with a Heisenberg-like Hamiltonian with a coordinate dependent exchange interaction\footnote{Ma P W, Woo C H, Dudarev S L 2008 \textit{Phys. Rev. B} \textbf{78} 024434}. Each of these interactions are parameterized by first-principles calculations. These simulations numerically solve equations of motion using an algorithm based on the second-order Suzuki-Trotter decomposition for the time evolution operator\footnote{Perera D, et al. 2014 \textit{J. Phys.: Conf. Ser.} \textbf{487} 012007}. Through calculation of the Fourier transform of space-displaced time-displaced correlation functions, vibrational and magnetic excitations have been studied. The application of an external magnetic field up to 10-T has now been included and has been shown to increase the characteristic frequencies of the single-spin-wave excitations. Two-spin-wave interactions have also been investigated.