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arXiv · 2307.13446

A versatile unitary transformation framework for an optimal bath construction in density-matrix based quantum embedding approaches

Quentin Marécat·Matthieu Saubanère
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Abstract

The performance of embedding methods is directly tied to the quality of the bath orbitals construction. In this paper, we develop a versatile framework, enabling the investigation of the optimal construction of the orbitals of the bath. As of today, in state-of-the-art embedding methods, the orbitals of the bath are constructed by performing a Singular Value Decomposition (SVD) on the impurity-environment part of the 1RDM, as originally presented in Density Matrix Embedding Theory (DMET). Recently, the equivalence between the SVD protocol and the use of unitary transformation, the so-called Block-Householder transformation, has been established. We present a generalization of the Block-Householder transformation by introducing additional flexible parameters. The additional parameters are optimized such that the bath-orbitals fulfill physically motivated constrains. The efficiency of the approach is discussed and exemplified in the context of the half-filled Hubbard model in one-dimension.

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Quentin Marécat, Matthieu Saubanère. 2023-07-25. A versatile unitary transformation framework for an optimal bath construction in density-matrix based quantum embedding approaches. https://doi.org/10.3390/computation11100203

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