Understanding the structural transformation, stability of medium-sized neutral and charged silicon clusters

Abstract

The structural and electronic properties for the global minimum structures of medium-sized neutral, anionic and cationic Sinμ (n = 20–30, μ = 0, −1 and +1) clusters have been studied using an unbiased CALYPSO structure searching method in conjunction with first-principles calculations. A large number of low-lying isomers are optimized at the B3PW91/6-311 + G* level of theory. Harmonic vibrational analysis has been performed to assure that the optimized geometries are stable. The growth behaviors clearly indicate that a structural transition from the prolate to spherical-like geometries occurs at n = 26 for neutral silicon clusters, n = 27 for anions and n = 25 for cations. These results are in good agreement with the available experimental and theoretical predicted findings. In addition, no significant structural differences are observed between the neutral and cation charged silicon clusters with n = 20–24, both of them favor prolate structures. The HOMO-LUMO gaps and vertical ionization potential patterns indicate that Si22 is the most chemical stable cluster, and its dynamical stability is deeply discussed by the vibrational spectra calculations.

General Synthesis of Heteroatom‐Doped Hierarchical Carbon toward Excellent Electrochemical Energy Storage

“…Figure exhibits the HOMO and LUMO of related materials, and the detailed data are listed in Table . Obviously, HOMO and LUMO of the materials are mostly confined on the graphite sheet, signifying that the excellent conductibility of the materials . Different from the HOMO and LUMO of C (Figure S2), the HOMO and LUMO of the SC‐1 are mainly localized at the center of the small model, showing that the active sites are derived from the central part .…”

Solvent Free Three-Component Synthesis of 2,4,5-trisubstituted-1H-pyrrol-3-ol-type Compounds from L-tryptophan: DFT-B3LYP Calculations for the Reaction Mechanism and 3H-pyrrol-3-one↔1H-pyrrol-3-ol Tautomeric Equilibrium

“…Several authors in the literature have used the Highest Occupied Molecular Orbital (HOMO) Lowest Occupied Molecular Orbital (LUMO) energy gap as a computational descriptor to understand kinetic stability. In general, a large energy gap corresponds to a high energy required for electron excitation [ 30 ] and it could be correlated with the nucleophile and electrophile character of reactants in organic reactions. To perform a comparison between the molecular stability of compounds 1 and 5 , computational calculations of HOMO-LUMO were performed.…”

Machine learning on drug-specific data to predict small molecule teratogenicity

“…After deriving a successful model for predicting teratological risk from drug structure, we sought to increase the predictive accuracy of our GBM by supplementing our features with information on “meta-structure 63 .” These factors included the following variables, which were calculated for all 611 sampled drugs within MOE (https://www.chemcomp.com/Products.htm)39, a suite of industry-grade chemical computing software for computer-aided molecular design. Each of the following meta-structural sets was encoded by chemically-significant cutoffs when available (e.g., druglikeness benchmarks from Lipinski’s Rule of Five (RO5) 64 ) or cutoffs determined from ROC analysis of extracted data): Druglikeness: the adherence of each molecule to Lipinski’s Rule of Five restrictions on the number of hydrogen-bond acceptors, hydrogen-bond donors, octanol-water partition effects, total polar surface area, molecular weight, and number of rotatable bonds for an attractive drug candidate 64 Energy of the Highest Occupied Molecular Orbital (HOMO): a quantum chemistry metric of the tendency of a molecule to donate an electron, as a proxy for drug stability and tendency to generate mutagenic free radicals 65 Energy of the Lowest Unoccupied Molecular Orbital (LUMO): a quantum chemistry metric of the tendency of a molecule to accept an electron, as a proxy for drug stability and tendency to generate mutagenic free radicals 65 Mutagenicity score, as calculated from in-built predictive models of the Ames test 40 pKa and most basic pKa …”

“…Energy of the Lowest Unoccupied Molecular Orbital (LUMO): a quantum chemistry metric of the tendency of a molecule to accept an electron, as a proxy for drug stability and tendency to generate mutagenic free radicals 65…”