Fundamental limitations of the eigenvalue continuation approach

In this work, we show that the eigenvalue continuation approach introduced recently by Frame et al. [Phys. Rev. Lett. 121, 032501 (2018)], despite its many advantages, has some fundamental limitations which cannot be overcome when strongly correlated many-body systems are considered. Taking as a working example a very simple system of several fermionic particles confined in a harmonic trap we show that the eigenvector continuation is not able to go beyond the accuracy of the sampling states. We support this observation within a very simple three-level model capturing directly this obstacle. Since mentioned inaccuracy cannot be determined self-consistently within the eigenvalue continuation approach, support from other complementary methods is needed.

Automated summary

In this work, the authors discuss the limitations of the eigenvalue continuation approach when applied to strongly correlated many-body systems. By using a simple system and model, they demonstrate that the eigenvector continuation is unable to surpass the accuracy of the sampling states. They propose the need for support from other complementary methods to overcome this inaccuracy.