First-principles Calculations under an External Electric Field: Electrochemical Reactions and Control of Electronic Structures

Abstract

Electronic structure study under an external electric field is one of the important subjects in the electronic device development and sustainable energy technologies. We developed a calculation method, called effective screening medium (ESM) method, to include the external electric field or bias potential within the density functional theory. In this article, the details of the ESM method are explained and two recent researches are reviewed. First, a simulation of the electrochemical reaction on a metal-water interface is reviewed. We have elucidated an electronic state modulation of metal surface during the reaction. Second, a study about the electronic structure of an ABC-stacked graphite thin film with or without an external electric field is reviewed. We have found that ferrimagnetic spin polarization occurs on the both surface sides of the thin film. The polarization is associated with the peculiar surface localized state that possesses the same characteristics as the edge-localized states of graphene nanoribbons. The spin polarization is, therefore, controllable by applying an external electric field.