Abstracts Book - IMRC 2018

• SA1-O033
OPTICAL PROPERTIES OF THE MOLECULE S8 PHYSISORBED ON A
GRAPHENE LAYER OR BETWEEN GRAPHITIC LAYERS
Juan Salvador Arellano 1 , Osiris Salas Torres 2 , Luis Fernando Magana 3
1 Universidad Autónoma Metropolitana, Ciencias Basicas, Mexico. 2 Esime zacatenco, , Mexico.
3
Instituto de Física - Universidad Nacional Autónoma de México, Estado Sólido, Mexico.
Using DFT (density functional theory), as implemented in Quantum espresso
computer code, the optical properties of an isolated S8 molecule physisorbed on
a 4x4 graphene layer (32 carbon atoms) are calculated. Also, the adsorption of
that molecule is studied when it is adsorbed between graphite AB layers with
different c cell parameters. Dependence of the results is analyzed and discussed
when using LDA, or GGA approximations, including Van der Walls corrections for
the GGA pseudopotential. The physisorption of the Sulphur molecule on the
pristine and periodic 4x4 supercell graphene layer is small, less than 50 meV, in
both cases, using LDA or GGA approximation for the pseudopotentials.
Relaxations were done for the Sulphur molecule when this was placed relatively
close to one of the graphite layers, changing the c cell parameter 6 to 10 Å.
Planar configurations are obtained for the molecule when c is small, but with
some distortion compared to the free configuration of the S8 molecule when
the c parameter is bigger. It was observed that the predicted c cell parameter
for graphite with GGA was much bigger than the experimental value, so, it was
necessary to take the Van der Walls (vdw) correction for S and C
pseudopotentials. Variable cell calculations for the entire system are on course,
their optical properties will be calculated for the equilibrium calculation that
could be obtained. The optical properties …
Keywords: MOLECULE S8, Graphene/Graphite, Optical properties
Presenting authors email: jsap@correo.azc.uam.mx