ISSN:
1600-5724
Source:
Crystallography Journals Online : IUCR Backfile Archive 1948-2001
Topics:
Chemistry and Pharmacology
,
Geosciences
,
Physics
Notes:
In Part 1 [Knop, Palmer & Robinson (1975). Acta Cryst. A31, 19-31] arrangements of point charges at the vertices of polyhedra of cubic and icosahedral symmetry were described which produce a zero electric-field gradient (ZEFG) at a reference point s0(0, 0, 0). Further infinite classes of ZEFG configurations have now been identified, among them regular polygons having particular metric properties relative to S0, and combinations of such polygons. Any ZEFG configuration of charges on a sphere can be generated by combining suitable irreducible (minimal) ZEFG sets of charges. The numbers J(n) of irreducible ZEFG sets of n equal charges of the same sign on a sphere are known only for n ≤ 4: J(1) = 0, J(2) = 0, J(3) = 1 (any three vertices of a regular octahedron, no two forming a centrosymmetric pair), and J(4) = 3 (any four vertices of a cube, no two forming a centrosymmetric pair).
Type of Medium:
Electronic Resource
URL:
http://dx.doi.org/10.1107/S0567739476000272
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