Biomedical subjects

Juan E Iglesias

Publications and source records attributed to Juan E Iglesias.

2 recordsLinked to original sources

PubMed2006

Enumeration of polytypes MX and MX2 through the use of the symmetry of the Zhdanov symbol.

The different close-packed polytypes MX and MX2 have been enumerated for each of the possible space groups by counting the corresponding Zhdanov symbols for each space group and period of stacking, P, by the use of elementary combinatorial techniques. In special cases, simple closed formulae are obtained for these numbers as functions of P. The symmetry properties of the Zhdanov symbol have been investigated with the help of its cyclotomic representation and the two-color symmetry point group thereof. Zhdanov-like rules have been developed for MX2 polytypes. The SiC cases have been generated to P = 18 under the ;1-exclusion' rule and the possible diamond polytypes have been examined.

Journal Article↗

PubMed2006

Zhdanov's rules work both ways.

The relationship between the space-group symmetry of a close packing of equal balls of repeat period P and the symmetry properties of its representing Zhdanov symbol is analyzed. Proofs are straightforward when some symmetry is assumed for the stacking, and it is investigated how this symmetry is reflected in the structure of the Zhdanov symbol. Most of these proofs are documented in the literature, with variable degrees of rigor. However, the proof is somewhat more involved when working backwards, i.e. when some symmetry properties for the Zhdanov symbol are assumed and the corresponding effect on the symmetry of the polytype structure it represents is investigated, which may explain why these proofs are avoided or shrugged off as ;easily seen', 'obvious' and the like.

Journal Article↗