Uma banca de DEFESA de DOUTORADO foi cadastrada pelo programa.
DISCENTE: ANDERSON GOMES VIEIRA
DATA: 15/10/2025
HORA: 14:00
LOCAL: Remota (On-line)
TÍTULO: Estudo teórico e computacional das propriedades eletrônicas e mecânicas de alótropos bidimensionais de carbono com hibridizações sp e sp2 via teoria do funcional da densidade (DFT)
PALAVRAS-CHAVES: Grafeno; Semicondutores; r��GY Nanofitas de r��GY Nanotubos de r��GY.
PÁGINAS: 118
GRANDE ÁREA: Ciências Exatas e da Terra
ÁREA: Física
RESUMO:

The search for new two-dimensional carbon networks with tunable electronic
properties has driven the study of allotropes that combine sp and sp 2
hybridizations. In this context, this work proposes r��GY a novel rectangular
graphyne sheet composed of phenyl blocks connected by acetylenic chains,
similar to hexagonal ��-graphyne This system is arranged on a rectangular
lattice, analogous to the recently synthesized biphenylene network (BPN). The
stability of this bidimensional material was investigated from different
perspectives, and its structural, electronic, and mechanical properties were
studied through calculations based on Density Functional Theory (DFT) and
molecular dynamics simulations. The results indicate that r��G is dynamically
stable, with a phonon spectrum free of imaginary modes and robust behavior
under elevated thermal conditions, as confirmed by simulations showing bond
integrity up to 700 K. In its original form, the rectangular graphyne behaves as
a semiconducting system, presenting pairs of highly localized states. These
features are directly related to the structural anisotropy of the network, since its
electronic states exhibit quasi-one-dimensional behavior embedded in the two-
dimensional structure. In addition, mechanical properties of the 2D sheet were
calculated, revealing elastic anisotropy, with Young’s modulus and Poisson’s
ratio depending on the orientation, which reinforces its potential for applications
in flexible devices. The electronic properties of nanoribbons based on the
r��G structure were also investigated. It was shown how the electronic structure
of these nanoribbons depends on width and edge type (armchair and zigzag).
Nanotubes derived from r��G were analyzed, demonstrating that the band gap
can be tuned by varying the diameter, which expands the electronic versatility of
the system. Therefore, these results highlight r��GY proposed in this work, as
a promising material for future applications, especially in electronic devices, and
encourage further investigations on the properties of 2D allotropes with sp–sp 2
hybridizations.

MEMBROS DA BANCA:
Externo à Instituição - 001.***.***-65 - ALEXANDRE CAVALHEIRO DIAS - UnB
Externo à Instituição - 600.***.***-75 - DIEGO RABELO DA COSTA - UFC
Presidente - 1548848 - EDUARDO COSTA GIRAO
Externo ao Programa - 1689475 - JONATHAN DA ROCHA MARTINS
Externo à Instituição - 655.***.***-53 - JOÃO ALBERTO SANTOS PORTO - UEMA
Interno - 1340442 - RAMON SAMPAIO FERREIRA

Cadastrada em: 16/09/2025