Dynamical properties of the Holstein chain from finite-temperature density matrix renormalization group method

We present density-matrix renormalization group results for spectral

functions and conductivities of the Holstein polaron and systems with

a finite electron density in a Holstein chain. Our numerical approach is

based on the selection of optimal phonons modes based on the importance

selection of single-site reduced density matrix eigenstates, called local basis

optimization. We combine this approach with purification to obtain

the low-temperature thermodynamics and extract polaron spectral

functions from real-time simulations [1]. In a next step, we optimize

the algorithm by using the time-dependent variational principle

and parallelization to compute the optical conductivity of the Holstein

polaron, the bipolaron, and for systems at a finite electron filling.

We discuss our results using the Born-Oppenheimer surface picture

for Holstein dimers [2].