Screening in Graphene: Response to External Static Electric Field and an Image-Potential Problem

Area of Science:

• Condensed Matter Physics
• Materials Science
• Quantum Chemistry

Background:

• Graphene's unique electronic properties make it a candidate for advanced electronic devices.
• Understanding graphene's response to external fields is crucial for device applications.

Purpose of the Study:

• To investigate the response of a free-standing graphene sheet to an external perpendicular static electric field.
• To determine the induced charge density distribution and its centroid.
• To analyze the impact of the electric field on image-potential states.

Main Methods:

• First-principles calculations
• Pseudopotential density-functional theory (DFT) approach
• Analysis of charge density distribution and centroid position

Main Results:

• The charge density distribution induced by the electric field was determined.
• The centroid of the induced extra density (zim) was found to be 1.048 Å at vanishing electric field.
• The dependence of zim on the electric field strength was obtained.
• A hybrid one-electron potential was constructed using the determined zim, leading to new image-potential state energies.

Conclusions:

• The study provides a detailed understanding of graphene's electronic response to electric fields.
• The calculated zim and its field dependence are key parameters for modeling graphene-based systems.
• The findings contribute to the development of novel graphene electronic devices.