The electron-phonon $(e\text{\ensuremath{-}}\mathrm{ph})$ interaction remains of great interest in condensed matter physics and plays a vital role realizing superconductors, charge density waves (CDW), polarons. We study the two-dimensional Holstein model for $e\text{\ensuremath{-}}\mathrm{ph}$ coupling using determinant quantum Monte Carlo across wide range its phase diagram as function temper...

On examining the stability of a Wigner Crystal (WC) in an ionic dielectric, two competitive effects due to Polaron formation are found to be important: (i) the screening of the Coulomb forces which destabilizes the crystal, compensated by (ii) the increase of the carrier mass (polaron mass). The quantum melting of the Polaron Wigner Crystal (PWC) is examined. By calculating the quantum fluctuat...

Polarons, the combined motion of electrons in a cloth of their lattice distortions, are a key transport feature in doped manganites. To develop a profound understanding of the colossal resistance effects induced by external fields, the study of polaron correlations and the resulting collective polaron behavior, i.e., polaron ordering and transition from polaronic transport to metallic transport...

Many-polaron systems with finite charge-carrier density are often encountered experimentally. However, until recently, no satisfactory theoretical description of these systems was available even in the framework of simple models such as the one-dimensional spinless Holstein model considered here. In this work, previous results obtained using numerical as well as analytical approaches are review...

We consider a polaron model where molecular rotations are important. Here the usual hopping between neighboring sites is affected directly by the electron-phonon interaction via a twist-dependent hopping amplitude. This model may be of relevance for electronic transport in complex molecules and polymers with torsional degrees of freedom, such as DNA, as well as in molecular electronics experime...

We present exact numerical data for the lowest-energy momentum eigenstates (yrast states) of a repulsive spin impurity in one-dimensional Bose gas using full configuration interaction quantum Monte Carlo (FCIQMC). As stochastic extension to diagonalization it is well suited study yrast states lattice-renormalized model gas. Yrast carry valuable information about dynamic properties slow-moving m...

A many-body coherent potential approximation (CPA) previously developed for the double exchange (DE) model is extended to include coupling to local quantum phonons. The Holstein-DE model studied (equal to the Holstein model for zero Hund coupling) is considered to be a simple model for the colossal magnetoresistance manganites. We concentrate on eeects due to the quantisation of the phonons, su...

Based on the Holstein double-exchange model and a highly efficient single cluster Monte Carlo approach we study the interplay of double-exchange and polaron effects in doped colossal magneto-resistance (CMR) manganites. The CMR transition is shown to be appreciably influenced by lattice polaron formation.