Reconstructions of Laser‐Driven Molecular Magnetic Fields: A Possible Approach to Probe Anomalous Magnetic Signatures

ABSTRACT

The magnetic field of laser‐driven currents in benzene, naphthalene, and anthracene is reconstructed from real‐space time‐dependent density‐functional theory (TDDFT) current densities by two methods: the quasi‐static Biot–Savart (BS) law and the current–magnetization (CMH) framework, in which each carrier generates a locally screened source that is driven by its motion relative to nearby ions. The CMH is a microscopic theory of induction which was built upon reproducing the BS field of a conducting copper wire, and we compare its predictions for molecular systems against the BS predictions. For the polar current driven by a normal‐incidence, linearly polarized 6.9 eV (180 nm) valence‐excitation pulse, the BS field is predominantly transverse, with a deep central null and an off‐center maximum on the carbon skeleton. The CMH field resolves additional framework‐localized, higher‐multipole structure that the continuum BS kernel averages out, including a quadrupolar in naphthalene, dominant lobes of opposite sign to BS, and a central stagnation point that changes from a vortex to a saddle between molecules. Because the CMH source is constructed from the motional field that enters spin–orbit coupling, CMH–type maps are candidate descriptors of relativistic or competing‐current magnetic signatures.