Hexagonal closest packing model

The (a) hexagonal and (b) face-centered cubic closest packing models. The spheres are considered to... 

For evaluation of 6 we have assumed that the virus would be hexagonally closest-packed in a two-dimensional array on the adsorbent surface where 6 equals unity. The quantity x was estimated to be 50 from space filling models where approximately 3% of a 27-nm diameter icosahedral virion face is estimated, on the basis of globular protein structure (12), to approach the surface of the solid close enough to displace interfacial water molecules. If our estimate is changed to 10 or 250, instead of a most probable value of about 50, Equation 2 predicts that the AGads will be shifted by only zb 4 kj mol, which is comparable to the uncertainty given by experimental data scatter. 

In Activity 4.1, students described and modeled crystalline solids according to the way their atoms packed into a regular structure. We found that their atoms could pack into face-centered, body-centered, or hexagonal-closest arrangements. Another way to understand the structure of a crystalline solid is to consider the bonding forces between its structural units. 

The Au(lll) face, which is the closest packed fee structure, is known to have the lowest surface energy among all possible fee crystal faces. The clean Au( 111) face surface was first approximated to be a /3 X >/3.R30° unit cell. A model with a uniaxially contracted top hexagonal layer was proposed and a charge-density-wave (CDW) structure was also proposed as an explanation of the LEED observations. ... 

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