Self-consistent quantum defect embedding theory

Quantum Defect Embedding theory (QDET) [1-3] is a many-body embedding scheme to describe strongly correlated electrons localized within a given region of a solid, for example the electronic states of spin defects in semiconductors and insulators. Despite several successes of QDET in describing the electronic properties of point-defects, this framework becomes inaccurate when a large hybridization exists between the electronic states of the bulk and those of the defect, or when the effective screened interaction of the active space is frequency dependent. We present a method to solve these problems, which includes a self-consistent treatment of the host and the defect through the iterative computation of the screening in the active space and in the entire system. We then demonstrate its accuracy by comparing QDET results with those of other embedding methods and accurate chemical solvers for defective clusters. Our approach retains the scalability of QDET to large systems and paves the way to compute total-energies and to perform structural optimizations of excited states.

[1] H. Ma, M. Govoni, and G. Galli, npj Comput. Mater. 6, 85 (2020).

[2] N. Sheng et al., J. Chem. Theory Comput. 18, 3512 (2022).

[3] C. Vorwerk et al., Nat. Comput. Sci. 2, 424 (2022).