Banca de QUALIFICAÇÃO: MATEUS SILVA RÊGO

Uma banca de QUALIFICAÇÃO de DOUTORADO foi cadastrada pelo programa.
DISCENTE: MATEUS SILVA RÊGO
DATA: 26/02/2024
HORA: 14:30
LOCAL: Presencial - Auditório do Departamento de Fisica/UFPI
TÍTULO: Electronic properties of graphyne sheets based on the 2D biphenylene network
PALAVRAS-CHAVES: nanocarbons; electronic structure; biphenylene; energy gap; density functional theory
PÁGINAS: 35
GRANDE ÁREA: Ciências Exatas e da Terra
ÁREA: Física
RESUMO:

Graphene holds promissing applications in the development of nanoelectronic
devices, but the lack of a band gap motivates the search of ways to tune its
electronic properties. Apart from doping, defects and nanoribbons, a more
radical alternative is to study carbon 2D forms with structures completely
different from the honeycomb lattice. A relevant example is the family of
graphynes, which are usually similar to graphene in structural terms, but
showing carbon atoms with sp and sp2 hybridizations. The density and details
of the distribution of acetylenic links allows for a variety of electronic signatures
for these systems. On the other hand, other graphyne forms based on non-
graphitic lattice have been proposed, which expands even further the physics
and chemistry of carbon at the nanoscale. Here we propose a graphyne system
based on the recently synthesized biphenylene sheet. Our calculations were
based on the Density Functional Theory (DFT), as implemented in the SIESTA
package. We demonstrate that this is a system with highly localized states
which also shows a spin-polarized semiconducting configuration. We study its
stability from different aspects and show that the system’s structural details
directly influence its highly anysotropic electronic properties. Finally we show
that the symmetry of the frontier states can be further modulated by the size of
the acetylenic chains forming the system.

MEMBROS DA BANCA:
Interno - 1548848 - EDUARDO COSTA GIRAO
Presidente - 1250015 - PALOMA VIEIRA DA SILVA
Interno - 1340442 - RAMON SAMPAIO FERREIRA