Assisted hopping and interaction effects in impurity models

TL;DR

This paper investigates a generalized Anderson impurity model with filling-dependent hopping, revealing that strong assisted hopping enhances local pairing correlations involving on-site and neighboring pairs.

Contribution

It introduces a generalized impurity model with filling-dependent hopping and demonstrates the emergence of enhanced local pairing correlations at large assisted hopping values.

Findings

Enhanced local pairing correlations at large assisted hopping.

Pairs fluctuate between on-site and nearest neighbor positions.

Numerical Renormalization Group methods used for analysis.

Abstract

We study, using Numerical Renormalization Group methods, the generalization of the Anderson impurity model where the hopping depends on the filling of the impurity. We show that the model, for sufficiently large values of the assisted hopping term, shows a regime where local pairing correlations are enhanced. These correlations involve pairs fluctuating between on site and nearest neighbor positions.