Faculté des sciences

Accuracy of downfolding based on the constrained random-phase approximation

Shinaoka, Hiroshi ; Troyer, Matthias ; Werner, Philipp

In: Physical Review B, 2015, vol. 91, no. 24, p. 245156

We study the reliability of the constrained random-phase approximation (cRPA) method for the calculation of low-energy effective Hamiltonians by considering multiorbital lattice models with one strongly correlated “target” band and two weakly correlated “screening” bands. The full multiorbital system and the effective model are solved within dynamical mean-field theory (DMFT) in a... More

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    Summary
    We study the reliability of the constrained random-phase approximation (cRPA) method for the calculation of low-energy effective Hamiltonians by considering multiorbital lattice models with one strongly correlated “target” band and two weakly correlated “screening” bands. The full multiorbital system and the effective model are solved within dynamical mean-field theory (DMFT) in a consistent way. By comparing the quasiparticle weights for the correlated bands, we examine how accurately the effective model describes the low-energy properties of the multiband system. We show that the violation of the Pauli principle in the cRPA method leads to overscreening effects when the interorbital interaction is small. This problem can be overcome by using a variant of the cRPA method which restores the Pauli principle.