Ab initio simulation of charged slabs at constant chemical potential

Abstract

Articles you may be interested inCommunication: Regularizing binding energy distributions and thermodynamics of hydration: Theory and application to water modeled with classical and ab initio simulations Communication: Thermodynamics of water modeled using ab initio simulations Ab initio chemical potentials of solid and liquid solutions and the chemistry of the Earth's core We present a practical scheme for performing ab initio supercell calculations of charged slabs at constant electron chemical potential , rather than at constant number of electrons N e . To this end, we define the chemical potential relative to a plane ͑or ''reference electrode''͒ at a finite distance from the slab ͑the distance should reflect the particular geometry of the situation being modeled͒. To avoid a net charge in the supercell, and thus make possible a standard supercell calculation, we restore the electroneutrality of the periodically repeated unit by means of a compensating charge, whose contribution to the total energy and potential is subtracted afterwards. The ''constant '' mode enables one to perform supercell calculation on slabs, where the slab is kept at a fixed potential relative to the reference electrode. We expect this to be useful in modeling many experimental situations, especially in electro-chemistry.

First-principles study of surface charging inLaAlO3/SrTiO3heterostructures

“…1(b)], but we will use post-processing corrections to convert the energies and electrostatic potentials to those of an auxiliary system consisting of the charged slab compensated by grounded metal "reference electrodes" at the supercell boundaries. 31 This allows us to separate the electrostatic effects associated with the addition of surface charge from the changes in surface energy. The purpose of introducing the "reference electrodes" in the auxiliary system is two-fold: (1) to prevent the divergence of the electrostatic potential due to the charged slab (same role as a compensating charge), and (2) to serve as a consistent reference for the comparison of the energies of surfaces with different charges.…”

“…More importantly, it is not clear how one would disentangle the properties of the interface and the surface, making it difficult to discuss the physics and also to present the results in a form that can productively be used for further analysis of similar systems (e.g., with different layer thicknesses). Instead, we focus on calculations for a charged LAO slab with a uniform CBC, and correct for spurious effects by adopting a methodology originally developed by Lozovoi et al 31 for charged metal surfaces, which we generalize here for the case of a dielectric slab.…”

“…Section II B describes the methodology involved in calculating the surface energies of neutral reconstructed as well as unreconstructed LAO surfaces from first principles. The approach developed by Lozovoi et al 31 to treat charged surface of metals is generalized to the treatment of charged surface of dielectrics, as systematically explained in Sec. II C. In Sec.…”

Ab Initio Electrochemistry: Exploring the Hydrogen Evolution Reaction on Carbon Nanotubes

“…The most elegant solution would be to treat electrons in the grand canonical ensemble, that is, to allow the number of electrons to change during the electronic structure self-consistency loop, which is equivalent to connecting the system to a fictitious potentiostat. 5,6 Unfortunately, convergence of the grand canonical Kohn-Sham equations is significantly slower than with a fixed number of electrons, limiting the method to small system sizes. Other suggested methods rely on extrapolating calculated energies from canonical, constant charge DFT simulations to constant electrode potential.…”

“…Several methods [5][6][7][8][9][10][11][12][13] have been proposed for correcting quantum chemical calculations to constant electrode potential. The most elegant solution would be to treat electrons in the grand canonical ensemble, that is, to allow the number of electrons to change during the electronic structure self-consistency loop, which is equivalent to connecting the system to a fictitious potentiostat.…”