Kinetic stability and NBO analysis of the C20-nAln nanocages (n=1-5) using DFT investigation

摘要

Following our quest for novel heterofullerenes, we have compared and contrasted substitution effects on C20-nAln. structures with n = 1-5, from kinetically view point at density functional theory (DFT). Structures with the odd numbered heteroatom (C19Al1, C17Al3 and C15Al5) appear open shell singlet ground state while the even ones (C18Al2-a, C18Al2-b, C16Al4-a and C16Al4-b) show closed shell singlet ground state. The high NBO charge distribution on the surface of C15Al5 nanocage provokes the more investigation for hydrogen storage. The overall trend for kinetic stability based on their band gap (Delta EHOMO-LUMO) in eV is C15Al5 (3.36) > C-20 (2.31) > C18Al2-a (2.25) > C17Al3 (1.96) >= C19Al1 (1.95) > C16Al4-b (1.86) > C16Al4-a (1.56) > C18Al2-b (1.03). Evidently, the C15Al5 heterofullerene is as the most kinetic stable species against electronic excitation from the occupied HOMO orbital to the corresponding unoccupied LUMO orbital and contains five aluminum atom alternatively in equatorial. Furthermore, C15Al5 displays the highest energy of HOMO (E-HOMO = -0.23321 a.u.), the lowest energy of LUMO (E-LUMO = -0.10981 a.u.), the lowest nucleophilicity (N = 3.11 eV), the lowest electrophilicity (omega = 3.24 eV), the highest hardness (eta = 3.36 eV) and the lowest softness (S = 0.15 eV) among the scrutinized species. Isolation of the two Al substitutions from each other by means of strong C=C double bonds, increases N (4.48 eV), omega (9.69 eV) making C18Al2-b as the most nucleophilic and electrophilic species. (C) 2021 Elsevier B.V. All rights reserved.