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In view of the numerous environmental hazards and health challenges linked to sulfur (iv) oxide (SO2), an indirect greenhouse gas, and the resultant need to develop efficient gas nanosensor devices, this research had as its principal focus on the theoretical evaluation of the gas sensing potential of metals: Ag, Au and Cu functionalized silicon-doped quantum dots (Si@QD) for the detection and adsorption of SO2 gas investigated using the first-principles density functional theory (DFT) computation at the B3LYP-D3(BJ)/def2-SVP level of theory. Eight (8) possible adsorption modes: SO2_O_Si@QD, SO2_O_Ag_Si@QD, SO2_O_Au_Si@QD, SO2_O_Cu_Si@QD, SO2_S_Si@QD, SO2_S_Ag_Si@QD, SO2_S_Au_Si@QD, and SO2_S_Cu_Si@QD were considered based on SO2 interactions with the studied materials at the -S and -O sites of the SO2 molecule. The counterpoise correction (BSSE) showed that five of the eight interactions had favorable Ead + BSSE values ranging from -0.31 to -1.98 eV. All the eight interactions were observed to be thermodynamically favorable with ΔG and ΔH ranging from -129.01 to -200.24 kcal/mol and -158.26 to -229.73 kcal/mol respectively. Results from the topology analysis reveal that van der Waals forces occurred the greatest at the gas-sensor interphase while SO2_S_ Cu_Si@QD is predicted to have the highest sensing potency based on the conductivity and recovery time estimations. These results confirm the potential efficient feasibility of real-world device application of the metals (Ag, Au, Cu) functionalized Si-doped QDs.

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RESUMEN

The effects of the curvature parameters on the energy eigenvalues and thermodynamic properties of quantum pseudoharmonic oscillator are investigated within the framework of nonrelativistic quantum mechanics. By employing Nikiforov-Uvarov method, the energy spectra are obtained and used to study the ordinary statistics and q-deformed superstatistics as a function of temperature in the presence and absence of the curvature parameters. It is shown that the q-deformed supertatistics properties of the quantum pseudoharmonic oscillator reduce to the ordinary statistical properties in the absence of the deformation parameter. Finally, our results are illustrated graphically to show the behaviour of the energy spectra and thermodynamic properties for the three curvature parameters:[Formula: see text].

RESUMEN

The study of intermolecular interactions is of great importance. This study attempted to quantitatively examine the interactions between cysteine (C3H7NO2S) and fullerene nanocages, C60, in vacuum. As the frequent introduction of elements as impurities into the structure of nanomaterials can increase the intensity of intermolecular interactions, nanocages doped with silicon and germanium have also been studied as adsorbents, C59Si and C59Ge. Quantum mechanical studies of such systems are possible in the density functional theory (DFT) framework. For this purpose, various functionals, such as B3LYP-D3, ωB97XD, and M062X, have been used. One of the most suitable basis functionals for the systems studied in this research is 6-311G (d), which has been used in both optimization calculations and calculations related to wave function analyses. The main part of this work is the study of various analyses that reveal the nature of the intermolecular interactions between the two components introduced above. The results of conceptual DFT, natural bond orbital, non-covalent interactions, and quantum theory of atoms in molecules were consistent and in favor of physical adsorption in all systems. Germanium had more adsorption energy than other dopants. The HOMO-LUMO energy gaps were as follows: C60: 5.996, C59Si: 5.309, and C59Ge: 5.188 eV at B3LYP-D3/6-311 G (d) model chemistry. The sensitivity of the adsorption increased when an amino acid molecule interacted with doped C60, and this capability could be used to design nanocarrier to carry cysteine amino acid.

RESUMEN

We report first-principles calculations of the structure and electronic structure of nitrogen-doped TiO2anatase as a function of the dopant depth below the (101) surface. Specifically we evaluate the depth dependence of the formation energy for a few positions of the N impurity, considering for both substitutional and interstitial sites. We find a significant advantage of interstitial over substitutional positions, and a mild dependence of this formation energy on depth. The lengths of the bonds surrounding the impurity also evolve smoothly with depth. Regarding the electronic structure, we report the main features of the intragap impurity states and the hole-related spin magnetization density surrounding the N impurity.

RESUMEN

In the present investigation, the feasibility of detecting the chlorofluoromethane (CFM) gas molecule onto the outer surface of pristine single layer boron nitride nanosheet (BNNS), as well as its aluminum (Al)- and gallium (Ga)-doped structures, was carefully evaluated. For achieving this goal, a density functional theory level of study using the Perdew, Burke, and Ernzerhof exchange-correlation (PBEPBE) functional together with a 6-311G(d) basis set has been used. Subsequently, the B3LYP, CAM-B3LYP, wB97XD, and M062X functionals with a 6-311G(d) basis set were also employed to consider the single-point energies. Natural bond orbital (NBO) and quantum theory of atoms in molecules (QTAIM) were implemented by using the B3LYP-D3/6-311G(d) method, and the results were compatible with the electronic properties. In this regard, the total density of states (TDOSs), the Wiberg bond index (WBI), natural charge, natural electron configuration, donor-acceptor natural bond orbital interactions, and the second-order perturbation energies are performed to explore the nature of the intermolecular interactions. All of the energy calculations and population analyses denote that by adsorbing of the gas molecule onto the surface of the considered nanostructures, the intermolecular interactions are of the type of strong chemical adsorption. Among the doped nanosheets, Ga-doped nanosheet has very high adsorption energy compared with other elements (i.e., Ga-doped > Al-doped > pristine). Generally, it was revealed that the sensitivity of the adsorption will be increased when the gas molecule interacts with decorated nanosheets and decrease the HOMO-LUMO band gap; therefore, the change of electronic properties can be used to design suitable nanosensors to detect CFM gas. Graphical abstract.

RESUMEN

We introduce an accurate and efficient algebraic technique for the computation of the vibrational spectra of triatomic molecules, of both linear and bent equilibrium geometry. The full three-dimensional potential energy surface (PES), which can be based on entirely ab initio data, is parametrized as a product Morse-cosine expansion, expressed in bond angle internal coordinates, and includes explicit interactions among the local modes. We describe the stretching degrees of freedom in the framework of a Morse-type expansion on a suitable algebraic basis, which provides exact analytical expressions for the elements of a sparse Hamiltonian matrix. Likewise, we use a cosine power expansion on a spherical harmonics basis for the bending degree of freedom. The resulting matrix representation in the product space is very sparse, and vibrational levels and eigenfunctions can be obtained by efficient diagonalization techniques. We apply this method to carbonyl sulfide, hydrogen cyanide, water, and nitrogen dioxide. When we base our calculations on high-quality PESs tuned to the experimental data, the computed spectra are in very good agreement with the observed band origins.