Cubic cell simple

Simple cubic cell (SC). This is a cube that consists of eight atoms whose centers are located at the comers of the cell Atoms at adjacent corners of the cube touch one another. 

Significant figure A meaningful digit in a measured quantity, 9,20-2 lq ambiguity in, 10 in inverse logarithms, 645-647 in logarithms, 645-647 Silicate lattices, 243 Silicon, 242-243 Silver, 540-541 Silver chloride, 433,443-444 Simple cubic cell (SC) A unit cell in which there are atoms at each comer of a cube, 246... 

Poi the simple cubic cell of Po (containing 1 atom in the origin) corresponds to a stacking sequence of type 1 square nets. 

Copper(I) nitride, Cu3N, crystals are also cubic, OPm3m, a0 = 3.814 A, with one molecule in the unit cell. Each N has an octahedral arrangement of six Cu atoms. Cu atoms have linear bonds to two N atoms and eight nearest Cu neighbors (see Figure 5.24). These are two sets of four planar Cu atoms bonded to the N atoms. The N atoms occupy sites for a simple cubic cell. To accommodate Cu and N in the P system, Cu atoms occupy P sites in an ABC sequence with N atoms in O sites. The P sites are three-quarters occupied and O sites are one-quarter occupied to give the notation 3 2P3/4Oi/4. 

PROBLEM 7.4.4. For a monoatomic cubic crystal consisting of spherical atoms packed as close as possible, given the choices of a simple cubic crystal (SCC atom at cell edges only this structure is rarely used in nature, but is found in a-Po), a body-centered cubic crystal (BCC, atom at comers and at center of body), and a face-centered cubic crystal (FCC body at face comers and at face centers), show that the density is largest (or the void volume is smallest) for the FCC structure (see Fig. 7.12). In particular, show that the packing density of spheres is (a) 52% in a simple cubic cell (b) 68% for a body-centered cell (c) 71% for a face-centered cubic cell. 

FIGURE 11.16 Arrangement of identical spheres in a simple cubic cell, (a) Top view of one layer of spheres, (bj Definition of a simple cubic cell, (cj Since each sphere is shared by eight unit cells and there are eight corners in a cube, there is the equivalent of one complete sphere inside a simple cubic unit cell. 

FIGURE 11.22 The relationship between the edge length (a) and radius (rj of atoms in the simple cubic cell, body-centered cubic cell, and face-centered cubic cell. 

Figure 11.22 summarizes the relationship between the atomic radius r and the edge length a of a simple cubic cell, a body-centered cubic cell, and a face-centered cubic cell. This relationship can be used to determine the atomic radius of a sphere if the density of the crystal is known, as the following example shows. 

If, for example, a face-centered crystal having four atoms per unit cell were to lose its face atoms to become a simple cubic cell with only one atom per unit cell, the volume per mole would be four times Table IV shows a comparison of 4Kq with from Eyring s papers. ... 

Begin by performing steps 1-3 in order to determine D,6, and sin2 8 and place them in tabular form as above. It is now possible to reject the primitive (simple) cubic cell possibility immediately because the separation between the sixth and seventh lines is not significantly larger than the separation between the fifth and sixth lines (see Problem 20.2 and Figure 20.22). 

In a simple cubic cell there are eight comer spheres. One-eighth of each belongs to the individual cell giving a total of one whole sphere per cell. In a body-centered cubic cell, there are eight comer spheres and one body-center sphere giving a total of two spheres per unit cell (one from the comers and one from the body-center). In a face-center sphere, there are eight comer spheres and six face-centered spheres (six faces). The total number of spheres would be four one from the comers and three from the faces. 

What is the coordination number of each sphere in RIS (a) a simple cubic cell, (b) a body-centered cubic... 

Reference [149] Cl scheme LSDA pseudopotentials from Ref. [266] simple cubic cell with a = 22 a.u. plane-wave cutoff of 20.9 Ry. 

---