20.500.12556/RUL-167837 Spectral function of a bipolaron coupled to dispersive optical phonons Using an efficient variational exact diagonalization method, we computed the electron removal spectral function within the framework of the Holstein-Hubbard model containing two electrons with opposite spins coupled to dispersive quantum optical phonons. We focus on how the interplay between the electron-phonon coupling and on-site Coulomb repulsion shapes the spectral function, a quantity directly relevant to angle-resolved photoemission spectroscopy (ARPES). Tuning the strengths of the electron-phonon coupling and the Hubbard interaction allows us to examine the evolution of the spectral properties of the system as it crosses over from a bound bipolaron to separate polarons. We find that phonon dispersion plays an important role: It substantially redistributes the spectral weight across the low- and the high-energy features and controls the emergence and the structure of distinct multiphonon continua. In regimes of strong electron-phonon coupling and low Coulomb repulsion, the spectral function exhibits a broad distribution reflecting bound bipolaronic states. Increasing the Coulomb repulsion weakens bipolaron binding, shifts the primary quasiparticle peak closer to polaronic behavior and confines the spectral weight near the Brillouin-zone center. Our results provide a framework for interpreting ARPES measurements in systems where phonon–mediated attraction competes with direct Coulomb repulsion. condensed matter physics quantum physics optical phonons polarons Holstein model Hubbard model electron-phonon coupling fizika kondenzirane snovi kvantna fizika optični fononi polaroni Holsteinov model Hubbardov model elektronsko-fononska sklopitev true false true Angleški jezik Slovenski jezik Članek v reviji 2025-03-14 13:03:10 2025-03-14 13:03:11 2025-03-15 04:06:39 0000-00-00 00:00:00 2025 0 0 Str. 115133-1-115133-12 iss. 11 Vol. 111 2025 0000-00-00 Zaloznikova Objavljeno NiDoloceno 0000-00-00 0000-00-00 0000-00-00 538.9 2469-9950 10.1103/PhysRevB.111.115133 229057027 PhysRevB.111.115133.pdf PhysRevB.111.115133.pdf 1 22A4FC911D7D7384DC04FBA830537175 b628fa9eab088be1157b58bbdb41faa888697cd5dbd9d2042d45081eb2db8ce0 81791a05-00cb-11f0-b232-0050569b8976 https://repozitorij.uni-lj.si/Dokument.php?lang=slv&id=200669 https://journals.aps.org/prb/abstract/10.1103/PhysRevB.111.115133 0 8961c9ad-00cb-11f0-b232-0050569b8976 https://repozitorij.uni-lj.si/Dokument.php?lang=slv&id=200670 Fakulteta za matematiko in fiziko 0 0 0