Optical gaps of F-center defects in LiF using many-body methods

Area of Science:

• Condensed matter physics
• Materials science
• Computational chemistry

Background:

• F-center defects impact wide-bandgap solid properties.
• Experimental and computational characterization of F-centers is challenging.
• Accurate modeling requires accounting for aperiodicity, lattice distortion, and polarization effects.

Purpose of the Study:

• To investigate bulk and surface F-center defects in LiF.
• To evaluate computationally efficient potentials for modeling these defects.
• To determine the optical gaps of bulk and surface F-centers.

Main Methods:

• Combined random phase approximation (RPA) based potentials with periodic electrostatic embedding.
• Evaluated single-pole exchange-correlation (1p-XC) and static-Coulomb hole screened exchange (st-COHSEX) potentials.
• Calculated optical gaps for bulk and surface F-center defects in LiF.

Main Results:

• The 1p-XC potential is suitable for modeling bulk and surface F-center defects.
• Predicted optical gap for bulk F-centers (5.24 eV) closely matches high-level quantum chemistry methods and experimental data.
• Identified a significantly lower optical gap (1.85 eV) for surface F-centers due to reduced confinement and increased lattice relaxation.

Conclusions:

• The 1p-XC approach provides an accurate and efficient method for studying F-center defects.
• Surface F-centers exhibit distinct electronic properties compared to bulk F-centers, with implications for materials applications.
• Further research into surface F-center defects is warranted due to their unique characteristics.