SKM 2023 – scientific programme

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TT: Fachverband Tiefe Temperaturen

TT 5: Correlated Electrons: Method Development

TT 5.7: Talk

Monday, March 27, 2023, 11:00–11:15, HSZ 204

Projective cluster-additve block-diagonalisation method — •Max Hörmann and Kai Phillip Schmidt — Institut für Theoretische Physik I, Universität Erlangen-Nürnberg, Staudtstraße 7, 91058 Erlangen

We present an efficient block-diagonalisation method that only relies on the lowest eigenvectors and eigenvalues and allows for a linked-cluster expansion. The method is applied to a low-field expansion of the transverse-field Ising model on the square lattice. Both the single spin-flip and bound-state dispersion is calculated perturbatively and non-perturbatively. The origin of the breakdown of the non-perturbative linked-cluster expansion for the bound-state dispersion at a critical field value is discussed and potential solutions to overcome this problem are examined.