ADAQ-SYM: Automated symmetry analysis of defect orbitals

Abstract

Quantum technologies like single photon emitters and qubits can be enabled by point defects in semiconductors, with the NV-center in diamond being the most prominent example. There are many different semiconductors, each potentially hosting interesting defects. The symmetry properties of the point defect orbitals can yield useful information about the behavior of the system, such as the interaction with polarized light. We have developed a tool to perform symmetry analysis of point defect orbitals obtained by plane-wave density functional theory simulations. The software tool, named ADAQ-SYM, calculates the characters for each orbital, finds the irreducible representations, and uses selection rules to find which optical transitions are allowed. The capabilities of ADAQ-SYM are demonstrated on several defects in diamond and 4H-SiC. The symmetry analysis explains the different zero phonon line (ZPL) polarization of the hk and kh divacancies in 4H-SiC.

Program summary

Program Title: ADAQ-SYM

CPC Library link to program files: https://doi.org/10.17632/th5362mzxt.1

Developer's repository link: https://github.com/WSten/ADAQ-SYM

Licensing provisions: GNU Affero General Public License Version 3

Programming language: Python 3

Nature of problem: Point defects in semiconductors can have localized orbitals in the band gap, these can be simulated with density functional theory (DFT). Automatically finding the symmetry properties (character and irreducible representation) of these orbitals would reduce manual work, and make the inclusion of symmetry properties in high-throughput screenings possible.

Solution method: ADAQ-SYM addresses this problem by calculating symmetry operator expectation values of orbitals computed with DFT, and translating these to characters and irreducible representation. The code also finds the symmetry allowed optical transitions.

Additional comments including restrictions and unusual features: Currently the code only works for DFT simulations at the Γ-point.