Formation of low effective-mass SSH bipolarons at strong coupling in the adiabatic regime

Determine whether Su–Schrieffer–Heeger (SSH) bipolarons with low effective mass form at strong electron–phonon coupling in the adiabatic regime characterized by low phonon frequencies (Ω/4t ≪ 1).

Background

Prior work has shown that Peierls/SSH-type coupling can stabilize light bipolarons in the anti-adiabatic regime, raising the possibility of bipolaronic high-temperature superconductivity. These conclusions, however, are primarily based on high phonon frequency calculations.

The adiabatic regime, relevant to many materials, poses significant computational challenges. It remains unresolved whether such light SSH bipolarons persist and form at strong coupling in the adiabatic limit, a key issue for assessing the viability of bipolaronic superconductivity in realistic systems.

References

It is not understood if the sharp transition observed in the effective mass for the SSH polaron survives and whether the SSH bipolarons with low effective mass may form at strong coupling in the adiabatic regime.

— Extrapolation of polaron properties to low phonon frequencies by Bayesian machine learning (2312.09991 - Kairon et al., 2023) in Introduction, paragraph preceding the sentence beginning “Motivated by this uncertainty…”