2004/04/22 by Marco Zoli, Arnab Das, A. N. Das · 1 citation
Engineering · Materials Science · Physics and Astronomy · #Magnetism in coordination complexes #Organic and Molecular Conductors Research #Perovskite Materials and Applications #cond-mat.str-el #cond-mat.supr-con
paper · pdf · doi:10.1088/0953-8984/16/21/009
published as J. Phys.: Cond.Matter, vol. 16, p. 3597 (2004) · To be published in J.Phys.:Condensed Matter
arxiv created 2004/04/22 · openalex publication_date 2004/05/14 · arxiv updated 2009/12/01 · openalex created_date 2025/10/10 · openalex updated_date 2026/07/28
An analytical variational method is applied to the molecular Holstein Hamiltonian in which the dispersive features of the dimension dependent phonon spectrum are taken into account by a force constant approach. The crossover between a large and a small size polaron is monitored, in one, two and three dimensions and for different values of the adiabatic parameter, through the behaviour of the effective mass as a function of the electron–phonon coupling. By increasing the strength of the intermolecular forces the crossover becomes smoother and occurs at higher e–ph couplings. These effects are more evident in three dimensions. We show that our modified Lang–Firsov method starts to capture the occurrence of a polaron self-trapping transition when the electron energies become of order of the phonon energies. The self-trapping event persists in the fully adiabatic regime. At the crossover we estimate polaron effective masses of order about 5–40 times the bare band mass according to the dimensionality and the value of the adiabatic parameter. Modified Lang–Firsov polaron masses are substantially reduced in two and three dimensions. There is no self-trapping in the antiadiabatic regime.