arXiv subjects

John H. Weare

Publications and source records attributed to John H. Weare.

3 recordsLinked to original sources

arXiv1994

C20: Fulleren, Bowl or Ring? New Results from Coupled-Cluster Calculations

Contrary to recent experimental evidence suggesting that the monocyclic ring is the most stable 20-atom carbon species, highly accurate calculations convincingly predict that the smallest fullerene, the dodecahedron C$_{20}$, has the lowest energy. A related corannulene-like bowl is nearly degenerate in energy to the fullerene. Thermodynamic considerations suggest that at formation temperatures of around 700 K the bowl should be the dominant species. The recent application of gradient corrections to LDA which supported the ring structure is qualitatively in error. (RK-94-02)

chem-ph↗

arXiv1994

Packing Transitions in Nanosized Li Clusters

Packing transitions in the lowest energy structures of Li clusters as a function of size have been identified via simulated annealing. For N>21, the large $p$ character of Li leads to unexpected ionic structures. At N~25, a packing pattern based on interpenetrating 13-atom icosahedra and similar to that of Na and K appears. This pattern persists until at N=55, where another transition to a structure based on a Mackay icosahedron occurs. For clusters of size 55 and 147, the optimized FCC structure representative of the bulk is still slightly higher in energy than the optimal MIC. (RK-94-03)

chem-ph↗

arXiv1994

Li$_5$ as a pseudorotating planar cluster

A pseudorotating state of Li$_5$ observed in a recent EPR experiment is investigated using the local density functional method. The calculated isotropic spin population indicates that a planar $C_{2v}$ structure is more consistent with the experimental result than a suggested trigonal bipyramid. A new pseudorotating state based on the planar structure is proposed.

chem-ph↗