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Title: Communication: Effect of accidental mode degeneracy on Raman intensity in 2D materials: Hybrid functional study of bilayer phosphorene

Abstract

Bulk black phosphorus has two optical phonon modes labeled as A g 2 and B 2u, respectively, that are nearly degenerate in frequency. However, density functional theory calculations using local or semi-local functionals cannot reproduce this degeneracy. In this, we propose a hybrid functional approach aided by van der Waals (vdW) force fields, which can accurately describe the lattice dynamic and electronic properties of both bulk and few-layer black phosphorus (phosphorene). Using this approach we show that in bilayer phosphorene, the two Raman modes derived from the B 2u and A g 2 modes could exhibit strong resonance as a result of the accidental degeneracy so that both modes could be observed in Raman experiment. Without the mode degeneracy, however, the Raman intensity of the B 2u-derived mode would be too weak to be observed. We further show that the accidental degeneracy is correlated to the applied strain, which enables Raman spectroscopy to be a powerful tool for characterizing built-in strains in 2D materials, e.g., due to the interaction with substrates, which has emerged as an important issue in vdW epitaxy.

Authors:
 [1];  [1]
  1. Rensselaer Polytechnic Inst., Troy, NY (United States). Dept. of Physics
Publication Date:
Research Org.:
Rensselaer Polytechnic Inst., Troy, NY (United States)
Sponsoring Org.:
USDOE Office of Science (SC); Lawrence Berkeley National Lab. (LBNL), Berkeley, CA (United States). National Energy Research Scientific Computing Center (NERSC)
OSTI Identifier:
1467841
Alternate Identifier(s):
OSTI ID: 1261218
Grant/Contract Number:  
SC0002623; AC02-05CH11231
Resource Type:
Journal Article: Accepted Manuscript
Journal Name:
Journal of Chemical Physics
Additional Journal Information:
Journal Volume: 145; Journal Issue: 2; Journal ID: ISSN 0021-9606
Publisher:
American Institute of Physics (AIP)
Country of Publication:
United States
Language:
English
Subject:
37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CHEMISTRY; 36 MATERIALS SCIENCE; 75 CONDENSED MATTER PHYSICS, SUPERCONDUCTIVITY AND SUPERFLUIDITY; phonons; normal modes; stress strain relations; tensor methods; local density approximations; monolayers; raman scattering; dielectric function; raman spectroscopy

Citation Formats

Sun, Yi-Yang, and Zhang, Shengbai. Communication: Effect of accidental mode degeneracy on Raman intensity in 2D materials: Hybrid functional study of bilayer phosphorene. United States: N. p., 2016. Web. doi:10.1063/1.4958460.
Sun, Yi-Yang, & Zhang, Shengbai. Communication: Effect of accidental mode degeneracy on Raman intensity in 2D materials: Hybrid functional study of bilayer phosphorene. United States. doi:10.1063/1.4958460.
Sun, Yi-Yang, and Zhang, Shengbai. Mon . "Communication: Effect of accidental mode degeneracy on Raman intensity in 2D materials: Hybrid functional study of bilayer phosphorene". United States. doi:10.1063/1.4958460. https://www.osti.gov/servlets/purl/1467841.
@article{osti_1467841,
title = {Communication: Effect of accidental mode degeneracy on Raman intensity in 2D materials: Hybrid functional study of bilayer phosphorene},
author = {Sun, Yi-Yang and Zhang, Shengbai},
abstractNote = {Bulk black phosphorus has two optical phonon modes labeled as Ag2 and B2u, respectively, that are nearly degenerate in frequency. However, density functional theory calculations using local or semi-local functionals cannot reproduce this degeneracy. In this, we propose a hybrid functional approach aided by van der Waals (vdW) force fields, which can accurately describe the lattice dynamic and electronic properties of both bulk and few-layer black phosphorus (phosphorene). Using this approach we show that in bilayer phosphorene, the two Raman modes derived from the B2u and Ag2 modes could exhibit strong resonance as a result of the accidental degeneracy so that both modes could be observed in Raman experiment. Without the mode degeneracy, however, the Raman intensity of the B2u-derived mode would be too weak to be observed. We further show that the accidental degeneracy is correlated to the applied strain, which enables Raman spectroscopy to be a powerful tool for characterizing built-in strains in 2D materials, e.g., due to the interaction with substrates, which has emerged as an important issue in vdW epitaxy.},
doi = {10.1063/1.4958460},
journal = {Journal of Chemical Physics},
number = 2,
volume = 145,
place = {United States},
year = {Mon Jul 11 00:00:00 EDT 2016},
month = {Mon Jul 11 00:00:00 EDT 2016}
}

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