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    Ab initio study of metal-decorated carbon and silicon prismanes as the selective CO2 adsorbents
    (World Scientific Publ Co Pte Ltd, 2023) Salem, Mahmoud A.; Jalali, Arman; Maleki, Fereshteh Gharehbaghi; Kumar, Ashish; Kaya, Savas; Sangwan, Renu
    In this paper, we conducted comprehensive analysis of the selective adsorption of CO2 by carbon and silicon prismanes along with metal ions. The results of calculations from B3LYP/6-31G(d,p) and M06-2X/6-31G(d,p) levels of theory show that Be2+, Mg2+, Ca2+ and Li+, Na+, K+ ions are bounded strongly enough to prismanes. The Be2+ ion binds more strongly to the C-8 H-8 cubane with binding energy 9.66eV compared to Li+, Na+, K+, Mg2+ and Ca2+ ions having binding energies 1.26, 0.63, 0.51, 4.60 and 3.36eV, respectively. Similar results were obtained for larger prismanes C(10)H(10 )and C12H12. Instead of binding energy, we determine the adsorption of gases on metal-ion prismane complex along with effect of temperature on different gas adsorption shows that C8H8_Mg2+ and C8H8_Be2+ are active adsorbents at temperatures above room temperature. It is also observed that in comparison to N-2 and CH4, CO2 interacts more strongly with all prismanes decorated with metal ions. These non-covalent interaction plots are used to study the prismane and metal-ion interaction. Comparable study of silicon prismanes with M06 2X/6-31G (d, p) basis set, in terms of binding energy, adsorption of gases on prismane along with temperature effect, also possesses similar selectivity to CO2 molecule with even higher adsorption energies. Thus, beryllium-decorated prismanes can be considered as promising adsorbents of carbon dioxide with good selectivity and high adsorption energy.
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    Interaction of dopants and functional groups adsorbed on the carbon fullerenes: Computational study
    (Elsevier, 2020) Salem, Mahmoud A.; Katin, Konstantin P.; Kaya, Savas; Kochaev, Alexei I.; Maslov, Mikhail M.
    We apply density functional theory to study the effective interaction between dopant atoms (B, N, Si, P) and functional groups (H, F, Cl, OH) on the surface of carbon fullerenes. Both dopant atoms and functional groups strongly interact through the carbon cage even in diametrically opposite positions. Interaction energies distribute in a wide range from 0.1 to 2 eV and non-monotonically depend on fullerene size and distance between dopants or functional groups. Such interaction cannot be described as a simple Coulomb repulsion or sum of dopants binding energies and cage strain energy. We identify some general trends in relative positions of dopants or functional groups in low-energy isomers. Para position of two functional groups is the most feasible for C-60 and larger cages. For lower fullerenes, ortho or other spaced positions may be more preferable. The interaction of foreign atoms embedded into the carbon cages is more complicated. The best relative positions intricately depend on the cage size and chemical nature of dopants. As a rule, ortho and para locations are feasible for C-60 and larger cages. However, some exceptions are observed. The effect of thermal vibrations on the considered interactions in doped or functionalized fullerenes is negligible in the temperature range from 300 to 1000 K.