Magnetization Dynamics from Time-Dependent Noncollinear Spin Density Functional Theory Calculations

A computational scheme, based on
a time-dependent extension of
noncollinear spin density functional theory, for the simultaneous
simulation of charge and magnetization dynamics in molecular systems
is presented. We employ a second-order Magnus propagator combined
with an efficient predictor-corrector scheme that allows us to treat
large molecular systems over long simulation periods. The method is
benchmarked against the low-frequency dynamics of the H–He–H
molecule where the magnetization dynamics can be modeled by the simple
classical magnetization precession of a Heisenberg–Dirac-van
Vleck Hamiltonian. Furthermore, the magnetic exchange couplings of
the bimetallic complex [Cu­(bpy)­(H2O)­(NO3)2(μ-C2O4)] (BISDOW) are extracted
from its low-frequency spin precession dynamics showing good agreement
with the coupling obtained from ground state energy differences. Our
approach opens the possibility to perform real-time simulation of
spin-related phenomena using time-dependent density functional theory
in realistic molecular systems.