4 research outputs found
Monte Carlo and DFT calculations on the corrosion inhibition efficiency of some benzimide molecules
Calculations using density functional theory (DFT) and Monte Carlo methods were performed on 2-methylbenzimidazole, 2-mercaptobenzimidazole, 2-aminobenzimidazole, benzotriazole, and benzimidazole to determine their corrosion inhibition efficiency. The molecular structure was optimized geometrically using DFT calculations at the B3LYP/6– 311 G++(d,p) and b2plypd3/aug-cc-pvdz basis set level in protonated and non-protonated species in gas and water. In this study, HOMO, LUMO, bandgap, ionization energy, electronegativity, hardness, softness, electrophilicity and nucleophilicity, electron transfer, back donation energy and condensed Fukui indices are used to assess a molecule's local reactivity. Theoretical investigations can precisely establish the geometrical dimensions of a molecule and correctly explain the quantum properties of inhibitors. The mechanism of interaction between inhibitors and metal surfaces in a specified molecule is studied using molecular dynamics. The benzimidazole functional groups absorbed energy linearly on metal surfaces, with quantum characteristics determined using density functional theory and an ab initio technique. Importantly, the findings of this conceptual model are consistent with the corrosion inhibition efficiency of earlier experimental investigations
Exploring electronic, optical, and phononic properties of MgX (X=C, N, and O) monolayers using first principle calculations
The electronic, the thermal, and the optical properties of hexagonal MgX
monolayers (where X=C, N, and O) are investigated via first principles studies.
Ab-initio molecular dynamic, AIMD, simulations using NVT ensembles are
performed to check the thermodynamic stability of the monolayers. We find that
an MgO monolayer has semiconductor properties with a good thermodynamic
stability, while the MgC and the MgN monolayers have metallic characters. The
calculated phonon band structures of all the three considered monolayers shows
no imaginary nonphysical frequencies, thus indicating that they all have
excellent dynamic stability. The MgO monolayer has a larger heat capacity then
the MgC and the MgN monolayers. The metallic monolayers demonstrate optical
response in the IR as a consequence of the metal properties, whereas the
semiconducting MgO monolayer demonstrates an active optical response in the
near-UV region. The optical response in the near-UV is beneficial for
nanoelectronics and photoelectric applications. A semiconducting monolayer is a
great choice for thermal management applications since its thermal properties
are more attractive than those of the metallic monolayer in terms of heat
capacity, which is related to the change in the internal energy of the system.Comment: RevTeX - pdfLaTeX, 9 pages with 8 included pdf figure
Optical conductivity enhancement and thermal reduction of BN-codoped MgO nanosheet: Significant effects of B-N atomic interaction
We investigate the electronic, the thermal, and the optical properties of
BN-codoped MgO monolayers taking into account the interaction effects between
the B and the N dopant atoms. The relatively wide indirect band gap of a pure
MgO nanosheet can be changed to a narrow direct band gap by tuning the B-N
attractive interaction. The band gap reduction does not only enhance the
optical properties, including the absorption spectra and the optical
conductivity, but also the most intense peak is shifted from the Deep-UV to the
visible light region. The red shifting of the absorption spectra and the
optical conductivity are caused by the attractive interaction. In addition,
both isotropic and anisotropic characteristics are seen in the optical
properties depending on the strength of the B-N attractive interaction. The
heat capacity is reduced for the BN-doped MgO monolayer, which can be referred
to changes in the bond dissociation energy. The bond dissociation energy
decreases as the difference in the electronegativities of the bonded atoms
decreases. The lower difference in the electronegativities leads to a weaker
endothermic process resulting in reduction of the heat capacity. An ab initio
molecular dynamics, AIMD, calculation is utilized to check the thermodynamic
stability of the pure and the BN-codoped MgO monolayers. We thus confirm that
the BN-codopant atoms can be used to gain control of the properties of MgO
monolayers for thermo- and opto-electronic devices.Comment: RevTeX - pdfLaTeX, 10 pages with 8 included pdf figure
Role of planar buckling on the electronic, thermal, and optical properties of Germagraphene nanosheets
We report the electronic, the thermal, and the optical properties of a
Germagraphene (GeC) monolayer taking into account buckling effects. The
relatively wide direct band gap of a flat GeC nanosheet can be changed by
tuning the planar buckling. A GeC monolayer has an sp hybridization in
which the contribution of an -orbital is half of the contribution of a
-orbital leading to stronger bonds compared to the
bonds. Increasing the planar buckling, the contribution of
an -orbital is decreased while the contribution of a -orbital is
increased resulting in a sp-hybridization in which the
bond becomes stronger than the bond. As a result, the
band gap of a buckled GeC is reduced and thus the thermal and the optical
properties are significantly modified. We find that the heat capacity of the
buckled GeC is decreased at low values of planar buckling, which is caused by
the anticrossing of the optical and the acoustic phonon modes affecting phonon
scattering processes. The resulting optical properties, such as the dielectric
function, the refractive index, the electron energy loss spectra, the
absorption, and the optical conductivity show that a buckled GeC nanosheet has
increased optical activities in the visible light region compared to a flat
GeC. The optical conductivity is red shifted from the near ultraviolet to the
visible light region, when the planar buckling is increased. We can thus
confirm that the buckling can be seen as another parameter to improve GeC
monolayers for optoelectronic devices.Comment: RevTeX - pdfLaTeX, 10 pages with 12 included pdf figure