For heavy elements, as well as phenomena involving the electron spins, it is well known that accurate modeling of the excited states and molecular properties requires the inclusion of relativistic effects into the electronic wave function. Because relativistic theories of the electron are inherently spin multi-component, time-dependent ab initio models of spintronic, magnetic, and heavy element containing systems need the ability to handle situations where electron spin can freely evolve in space and time, moving about in any given direction. Most conventional methods employed in the modeling electronic dynamics, such as real-time time-dependent density functional theory, are not flexible enough to handle the additional spin degrees of freedom. The primary problem lies in the so-called “spin collinearity constraint”, which requires that orbital spin is fixed in time. While this constraint is appropriate for a great variety of physical situations, it is inappropriate for many systems where relativistic effects are necessary, since within relativistic theory spin does not yield good quantum numbers, and specific interaction terms between pairs of electron spins and between the electron spins and their orbital motion. This work presents our recent development of time-dependent relativistic methods that enable one to describe spin dynamics within a first-principles framework.

Time-dependent two-component relativistic spin dynamics

253rd National Meeting (2017)

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