DMRG on Top of Plane-Wave Kohn–Sham Orbitals: A Case Study of Defected Boron Nitride

Abstract

In this paper, we analyze the numerical aspects of the inherently multi-reference density matrix renormalization group (DMRG) calculations on top of the periodic Kohn-Sham density functional theory (DFT) using the complete active space (CAS) approach. The potential of the framework is illustrated by studying hexagonal boron nitride (hBN) nano-flakes embedding a charged single boron vacancy point defect by revealing a vertical energy spectrum with prominent multi-reference character. We investigate the consistency of the DMRG energy spectrum from the perspective of sample size, basis size, and active space selection protocol. Results obtained from standard quantum chemical atom-centered basis calculations and plane-wave based counterparts show excellent agreement. Furthermore, we also discuss the spectrum of the periodic sheet which is in good agreement with extrapolated data of finite clusters. These results pave the way toward applying DMRG method in extended correlated solid state systems, such as point qubit in wide band gap semiconductors.

A multiconfigurational study of the negatively charged nitrogen-vacancy center in diamond

“…Depending on the cluster size, the energy separations change but the ordering of the states does not change. A similar trend of the cluster-size dependence was reported in the complete-active space approach, using DFT Kohn-Sham orbitals and density-matrix renormalization group [61]. This trend can be understood by the fact that higher-energy levels have stronger electron correlations which requires inclusion of more empty orbitals in the active space.…”

Density functionals with asymptotic-potential corrections are required for the simulation of spectroscopic properties of materials

“…65,66,72 Of significance, model-compound calculations have also been shown to converge to the same results as obtained using analogous calculations on 2D periodic defect models. 72,75 Nevertheless, these generic results are not expected to apply to the charge-transfer transitions of V N − considered herein. In 3D materials, dielectric screening of long-range interactions can be critical to spectroscopic properties, but this effect does not apply here to the properties of 2D materials.…”

Highly tunable magneto-optical response from magnesium-vacancy color centers in diamond

“…Many-body electronic excitation spectrum was computed using the DMRG approach 32 applied on top of periodic Kohn-Sham orbitals 33 . DFT and DMRG simulations were performed using the Quantum Espresso 34,35 , and the Budapest DMRG package 36 , respectively.…”