Atomistic Corrective Scheme for Supercell Density Functional Theory Calculations of Charged Defects

Abstract

A new method to correct formation energies of charged defects obtained by supercell density-functional calculations is presented and applied to bulk, surface, and low-dimensional systems. The method relies on atomistic models and a polarizable force field to describe a material system and its dielectric properties. The polarizable force field is based on a minimal set of fitting parameters, it accounts for the dielectric screening arising from ions and electrons separately, and it can be easily implemented in any software for atomistic molecular dynamics simulations. This work illustrates both technical aspects and applications of the new corrective scheme. The method is tested on systems in vacuo to validate the energy scheme. It is applied to charged defects in the bulk and at the surface of realistic materials to achieve comparison with published results obtained by using available corrective schemes based on continuum electrostatics treatments. Moreover, to demonstrate its generality, the method is used to correct the formation energy obtained by DFT of a singly negatively charged S vacancy in monolayer, bilayer, trilayer and bulk MoS2.

Erratum: Charged Point Defects in the Flatland: Accurate Formation Energy Calculations in Two-Dimensional Materials [Phys. Rev. X 4 , 031044 (2014)]

“…This change in the screening is the cause for the two length scales. One could then fit only the energies in the weak screening regime with a low-order polynomial, if such large supercells are computationally tractable [3]. Alternatively, we found that the energies can be well fitted in both regimes when the second-order polynomial is appended with an exponential term:…”

“…This issue was first pointed out by Noh et al [1] (and later on reported at least in Refs. [2,3]), who suggested using a fifth-order polynomial for the fitting.…”

Reorganization energy and polaronic effects of pentacene on NaCl films

“…As a consequence, the unit cell carries an electric dipole, while the shape of the associated field is a modeling artifact. In the literature, two methods have been proposed to compensate for this: (i) extrapolation to the dilute limit by finite-size scaling [29] and (ii) a posteriori corrections based on dielectric models [30][31][32].…”

Reorganization energy and polaronic effects of pentacene on NaCl films

“…As a consequence, the unit cell carries an electric dipole, while the shape of the associated field is a modeling artifact In the literature, two methods have been proposed to compensate for this: (i) extrapolation to the dilute limit by finitesize scaling 19 (ii) a posteriori corrections based on dielectric models [20][21][22] .…”