20.500.12556/RUL-154891 Light bipolarons in a system of electrons coupled to dispersive optical phonons We investigate the ground-state properties of the bipolaron coupled to quantum dispersive optical phonons in the one-dimensional Holstein-Hubbard model. We concentrate on the interplay between the phonon dispersion and the Coulomb repulsion and their mutual effect on the bipolaron effective mass, the binding energy, and the phase diagram. Most surprisingly, the sign of the curvature of the optical phonon dispersion plays a decisive role in the bipolaron binding energy in the presence of the Coulomb repulsion $U$. In particular, when the sign of the phonon dispersion curvature matches the sign of the electron dispersion curvature, the bipolaron remains bound in the strong-coupling limit even when $U \to \infty$ and the binding emanates from the exchange of phonons between two electrons residing on adjacent sites. At moderate electron-phonon coupling a light bipolaron exists up to large values of $U$. Finally, an intuitive explanation of the role of the phonon dispersion on the bipolaron binding energy is derived using the strong-coupling limit where the binding emanates from the exchange of phonons between two electrons residing on adjacent sites which leads to enhanced stability of bipolarons at elevated Coulomb repulsion. bipolaronic systems phonons phononic dispersion electron-phonon interaction electron-phonon coupling optical phonons 1-dimensional systems Holstein model variational wave functional methods condensed matter materials applied physics true false true Angleški jezik Slovenski jezik Članek v reviji 2024-03-07 11:16:27 2024-03-07 11:16:27 2024-09-25 04:18:32 0000-00-00 00:00:00 2024 0 0 8 str. iss. 6, art. 064304 Vol. 109 Feb. 2024 0000-00-00 PostprintKoncna Objavljeno NiDoloceno 0000-00-00 0000-00-00 0000-00-00 53 2469-9969 10.1103/PhysRevB.109.064304 185285123 2311.12403_(3).pdf 2311.12403_(3).pdf 1 81EC8333FFA57E2696AC700BD040A9B5 596a2b675d52f6f583fdaec4919b868e0c71410dc59e12fbcc35368a5682c4b4 1d8c418f-7a40-11ef-b232-0050569b8976 https://repozitorij.uni-lj.si/Dokument.php?lang=slv&id=191805 https://journals.aps.org/prb/abstract/10.1103/PhysRevB.109.064304 1 c3931be9-dc6b-11ee-966c-0050569b8976 https://repozitorij.uni-lj.si/Dokument.php?lang=slv&id=181529 Fakulteta za matematiko in fiziko 0 0 0