In this study, the adsorption of gases (CH4, CO, H2, NH3, and NO) onto Al12Si12 nanocages was theoretically investigated using density functional theory. For each type of gas molecule, two different adsorption sites above the Al and Si atoms on the cluster surface were explored. We performed geometry optimization on both the pure nanocage and nanocages after gas adsorption and calculated their adsorption energies and electronic properties. The geometric structure of the complexes changed slightly following gas adsorption. We show that these adsorption processes were physical ones and observed that NO adsorbed onto Al12Si12 had the strongest adsorption stability. The E g (energy band gap) value of the Al12Si12 nanocage was 1.38 eV, indicating that it possesses semiconductor properties. The E g values of the complexes formed after gas adsorption were all lower than that of the pure nanocage, with the NH3–Si complex showing the greatest decrease in E g. Additionally, the highest occupied molecular orbital and the lowest unoccupied molecular orbital were analyzed according to Mulliken charge transfer theory. Interaction with various gases was found to remarkably decrease the E g of the pure nanocage. The electronic properties of the nanocage were strongly affected by interaction with various gases. The E g value of the complexes decreased due to the electron transfer between the gas molecule and the nanocage. The density of states of the gas adsorption complexes were also analyzed, and the results showed that the E g of the complexes decreased due to changes in the 3p orbital of the Si atom. This study theoretically devised novel multifunctional nanostructures through the adsorption of various gases onto pure nanocages, and the findings indicate the promise of these structures for use in electronic devices.

/pdf/structural-and-electronic-properties-of-h2-co-ch4-no-and-nh3-1qcmi10n.pdf

Structural and electronic properties of H2, CO, CH4, NO, and NH3 adsorbed onto Al12Si12 nanocages using density functional theory

César Castillo-Quevedo, Edgar Paredes-Sotelo, Carlos Emiliano Buelna-Garćıa, Edwin Rene Hoil-Canul, Jhonny Robert Mis-May, Jarbin Barrios-Dı́az, Martha Fabiola Martin-del-Campo-Solis, Edgar Zamora-Gonzalez, Adolfo López-Sánchez, Jesús Ramón Cob-Cantu, Jorge Briceño-Mena, Freddy Francisco Agust́ın-Argüello, Tzarara López-Luke, Gerardo Mart́ınez-Guajardo, ∗ and Jose Luis Cabellos † Departamento de Fundamentos del Conocimiento, Centro Universitario del Norte, Universidad de Guadalajara, Carretera Federal No. 23, Km. 191, C.P. 46200, Colotlán, Jalisco, México Departamento de Investigación en Poĺımeros y Materiales, Edificio 3G. Universidad de Sonora. Hermosillo, Sonora, México Universidad Politécnica de Tapachula, Carretera Tapachula a Puerto Madero km 24+300, San Benito, Puerto Madero C.P. 30830, Tapachula, Chiapas, México Instituto de Investigación en Metalurgia y Materiales, Universidad Michoacana de San Nicolás de Hidalgo, Edificio U, Ciudad Universitaria, Morelia, Mich, 58030, México Unidad Académica de Ciencias Qúımicas, Área de Ciencias de la Salud, Universidad Autónoma de Zacatecas, Km. 6 carretera Zacatecas-Guadalajara s/n, Ejido La Escondida C. P. 98160, Zacatecas, Zac. Universidad Politécnica de Tapachula, Carretera Tapachula a Puerto Madero km 23+300, San Benito, Puerto Madero C.P. 30830, Tapachula, Chiapas, México (Dated: March 22, 2022)

Structures and stability of the Cu$_{38}$ cluster at finite temperature

Since the first detection of CH molecule in interstellar medium (ISM), more than 270 molecules have been identified in various astronomical sources in ISM. These molecules include big complex ones, such as fullerene (C60) and polycyclic aromatic hydrocarbons (PAHs), which are the main components of carbonaceous dust. Dust surface chemistry plays an important role in explaining the formation of interstellar molecules. However, many of the dust surface chemical parameters, such as the adsorption energies, are still of uncertainty. Here we present a study of the adsorption of water (H2O), ammonia (NH3), and carbon dioxide (CO2) on graphene-like substrate within the framework of density functional theory (DFT). We used Gaussian 16 software and adopted the corrected generalized gradient approximation (GGA) with the Perdew–Burke–Ernzerhof (PBE) functions. We determined the optimal accretion position of the studied molecules on the graphene-like surface and calculated the adsorption energies. Furthermore, according to the density of states and molecular orbitals of the adsorbed states, we analyzed the charge transfer between the molecules and the graphene-like surface. These results can provide more accurate parameters for calculating the chemical reaction rates on the dust surface, thus contributing to the understanding of dust-surface reactions in ISM.

/pdf/quantum-mechanical-modeling-of-interstellar-molecules-on-9oc0t83f.pdf

Quantum mechanical modeling of interstellar molecules on cosmic dusts: H2O, NH3, and CO2

The relative populations of Cu38 isomers depend to a great extent on the temperature. Density functional theory and nanothermodynamics can be combined to compute the geometrical optimization of isomers and their spectroscopic properties in an approximate manner. In this article, we investigate entropy-driven isomer distributions of Cu38 clusters and the effect of temperature on their IR spectra. An extensive, systematic global search is performed on the potential and free energy surfaces of Cu38 using a two-stage strategy to identify the lowest-energy structure and its low-energy neighbors. The effects of temperature on the populations and IR spectra are considered via Boltzmann factors. The computed IR spectrum of each isomer is multiplied by its corresponding Boltzmann weight at finite temperature. Then, they are summed together to produce a final temperature-dependent, Boltzmann-weighted spectrum. Our results show that the disordered structure dominates at high temperatures and the overall Boltzmann-weighted spectrum is composed of a mixture of spectra from several individual isomers.

/pdf/relative-populations-and-ir-spectra-of-cu38-cluster-at-14132hqu.pdf

Jhonny Robert Mis-May

Papers

Relative Populations and IR Spectra of Cu38 Cluster at Finite Temperature Based on DFT and Statistical Thermodynamics Calculations

Structures and stability of the Cu$_{38}$ cluster at finite temperature