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Download fileQuantum Embedding Theory for Strongly Correlated States in Materials
journal contribution
posted on 19.03.2021, 13:03 authored by He Ma, Nan Sheng, Marco Govoni, Giulia GalliQuantum embedding theories are promising
approaches to investigate
strongly correlated electronic states of active regions of large-scale
molecular or condensed systems. Notable examples are spin defects
in semiconductors and insulators. We present a detailed derivation
of a quantum embedding theory recently introduced, which is based
on the definition of effective Hamiltonians. The effect of the environment
on a chosen active space is accounted for through screened Coulomb
interactions evaluated using density functional theory. Importantly,
the random phase approximation is not required, and the evaluation
of virtual electronic orbitals is circumvented with algorithms previously
developed in the context of calculations based on many-body perturbation
theory. In addition, we generalize the quantum embedding theory to
active spaces composed of orbitals that are not eigenstates of Kohn–Sham
Hamiltonians. Finally, we report results for spin defects in semiconductors.