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for Avogadro's number of atoms, one twelfth of which might yield a mass of something like 1 gram.

The new International System of Units may let us select an integer value for Avogadro's number. Some might prefer an integer that's divisible by 12, so that an integer number of 12C atoms may be associated with a gram of mass [1,2]. For educational as well as practical reasons it may also help to choose a physically-meaningful definition, within measurement error of the current numeric value. Cubes of diamond face-centered-cubic Si and (much rarer) face-centered-cubic C have been proposed, but these structures don't have naturally occurring facets (or numbers of atoms generally divisible by 12). We show here that graphite prisms formed by stacking m hexagonal graphene sheets, with m ≡ 51,150,060 carbon-12 atoms on each side, are a natural solution to this challenge.

Home link: a multiple of 12 for Avogadro

Note: The numbered sections under Navigation at left represent sections of a draft paper.

Footnotes

1. Divisibility by 12 is of marginal value for two reasons, however. The first is that the definition of the gram will be decoupled from that a C-12 atom in the new-SI. The second is that binding-energy mass-deficits give mass-standards a dependence on bonding configuration that molar-standards don't have to deal with.
2. P. Fraundorf and Melanie Lipp (2016) "Molar standards & information units in the `new-SI'" draft pdf.