Implementation of density functional embedding theory within the projector-augmented-wave method and applications to semiconductor defect states

Abstract

We report a new implementation of the density functional embedding theory (DFET) in the VASP code, using the projector-augmented-wave (PAW) formalism. Newly developed algorithms allow us to efficiently perform optimized effective potential optimizations within PAW. The new algorithm generates robust and physically correct embedding potentials, as we verified using several test systems including a covalently bound molecule, a metal surface, and bulk semiconductors. We show that with the resulting embedding potential, embedded cluster models can reproduce the electronic structure of point defects in bulk semiconductors, thereby demonstrating the validity of DFET in semiconductors for the first time. Compared to our previous version, the new implementation of DFET within VASP affords use of all features of VASP (e.g., a systematic PAW library, a wide selection of functionals, a more flexible choice of U correction formalisms, and faster computational speed) with DFET. Furthermore, our results are fairly robust with respect to both plane-wave and Gaussian type orbital basis sets in the embedded cluster calculations. This suggests that the density functional embedding method is potentially an accurate and efficient way to study properties of isolated defects in semiconductors.

Charged‐cell periodic DFT simulations via an impurity model based on density embedding: Application to the ionization potential of liquid water

“…Future applications of the method will involve ionic crystals—a class of systems where the Madelung fields are very large and provide a more stringent test of the reliability of the method. Additionally, we plan to embark on less straightforward applications inspired by the work of Carter and coworkers and others, involving embedding finite subsystems described by wavefunction methods (like coupled cluster methods, which are not yet fully developed for solid‐state systems) inside infinite or semi‐infinite subsystems. This will open the door to the high‐accuracy calculations of ionization potentials and electron affinities of condensed‐phase molecular systems.…”

Prediction of a low-temperature N 2 dissociation catalyst exploiting near-IR–to–visible light nanoplasmonics

“…S4A) was carved out from the slab, with the remaining 94 Au atoms designated as the environment. The embedding potential, V emb , was determined from periodic PW-DFT using a modified VASP version 5.3.3 code via maximization of the extended Wu-Yang functional, W ( 64 ). W is a functional of the densities of the full system (represented by ∂ E ref /∂ V emb ), cluster (ρ cl , via its energy ), and the environment (ρ env , via its energy ) …”

“…The potential gradient is therefore defined as resulting in the recovery of the ground-state slab electron density from the sum of the density of the fragments within DFT ( 40 , 64 ). The embedded cluster and environment energies were obtained from modified one-electron KS Hamiltonians ( H °) …”

Formulation and Implementation of Density Functional Embedding Theory Using Products of Basis Functions

“…All-electron embedding calculations in this context are even more involved as different grids (both different from molecular grids) are used for the core and valence levels in the periodic DFT codes. 10 In this work, we focus on developing an embedding potential representation in the context of unique-potential density functional embedding theory (DFET) to seamlessly link periodic DFT using Gaussian basis functions with molecular wave function solvers. Although implemented and tested for DFET, the formulation can be applied to other embedding methods, based on embedding potentials, such as potential functional embedding theory (PFET) 12 and others.…”