Orbital Angular Momentum Currents and Textures in a Multiorbital Double Helix

Abstract

The microscopic origin of chirality induced spin selectivity (CISS) in biomolecular structures has traditionally been discussed in terms of spin orbit coupling and spin angular momentum. However, orbital angular momentum (OAM) is increasingly recognized as a more direct electronic response to molecular chirality. A helical hopping network built only from s orbitals can support an itinerant orbital moment and an orbital Edelstein response, but such a basis has no local atomic OAM and therefore omits the complementary contribution arising from coherence among active p orbitals. Here we construct a six-band multiorbital double helix model parameterized by characteristic B form DNA geometry and hopping scales. The model incorporates major minor groove asymmetry, an axial base pair offset representing stagger, and compositional inequivalence between the two strands, providing structural control parameters with which the orbital response can be tuned. Inter strand hybridization generates a full three component atomic OAM texture in the corotating local helical frame, including a radial component absent in the corresponding single helix model. We separately evaluate the itinerant OAM using the Bloch wave packet formulation of orbital magnetization and identify an additional inter-strand circulation channel unique to the double-helix connectivity. The resulting atomic and itinerant responses have distinct microscopic origins, magnitudes, and temperature dependences, establishing a multiorbital framework for geometry controlled angular momentum generation and transport in chiral molecular conductors.