Quantum molecular interpretation of the absorption spectra of Na5, Na6, and Na7 clusters

One-step functionalization of multi-walled carbon nanotubes with Ag/polymer under γ-ray irradiation

We reported an easy strategy of using γ-ray irradiation to functionalize multi-walled carbon nanotubes (MWCNTs) without the use of aggressive acid treatment, all in a single processing step. In this paper, we tried to decorate MWCNTs with Ag nanoparticles relying on covalently bonded polymers, via one-step covalent grafting of the polymer to the surface of MWCNTs, and simultaneous reducing of Ag(+) ions to Ag which are then efficiently anchored onto the MWCNTs. Herein, the polymer involved was the commercially available polymer poly(vinyl alcohol) (PVA) and two of its derivatives, polyvinylacetone with ketalization degree D(H) = 0.22 and 0.53. It is envisioned that this simple but efficient method could be extended to fabricate other CNT-based hybrids for both theoretical study and applications in biological and technological fields.

High accuracy ab initio studies of Li6+, Li6−, and three isomers of Li6

The structures and energetics of Li(6) (+), Li(6) (-) and three isomers of Li(6) are investigated using the coupled-cluster singles, doubles and perturbative triples [CCSD(T)] method with valence and core-valence correlation consistent basis sets of double- to quadruple-zeta quality (cc-pVXZ and cc-pCVXZ, where X=D-Q). These results are compared with qualitatively different predictions by less reliable methods. Our results conclusively show that the D(4h) isomer is the global minimum structure for Li(6). It is energetically favored over the C(5v) and D(3h) structures by about 5.1 and 7.1 kcal mol(-1), respectively, after the inclusion of the zero-point vibrational energy (ZPVE) correction. Our most accurate total atomization energies are 123.2, 117.6, and 115.7 kcal mol(-1) for the D(4h), C(5v), and D(3h) isomers, respectively. Comparison of experimental optical absorption spectra with our computed electronic spectra also indicate that the D(4h) isomer is indeed the most stable structure. The cation, anion, and some higher spin states are investigated using the less expensive cc-pCVDZ basis set. Adiabatic ionization energies and electron affinities are reported and compared with experimental values. Predictions of molecular properties are found to be sensitive to the basis set used and to the treatment of electron correlation.