diff --git a/src/9_crystal_structure_solutions.md b/src/9_crystal_structure_solutions.md index 8a781eeafb3b5f7e08a0f0767231b53ae3ab5c96..69434f01af9bd01fd5a0f9ac0d169743bf7e0dee 100644 --- a/src/9_crystal_structure_solutions.md +++ b/src/9_crystal_structure_solutions.md @@ -20,7 +20,7 @@ $$ \mathbf{a}_3 &= \frac{a}{2}(\mathbf{\hat{y}} + \mathbf{\hat{z}}). \end{align} $$ -With respect to the conventional unit cell, the basis in fractional coordinates is $\bigcirc(0,0,0)$, $\bigcirc(1,0,0)$, $\bigcirc(0,1,0)$ and $\bigcirc(0,0,1)$. +With respect to the conventional unit cell, the basis in fractional coordinates is $\bigcirc(1/2,1/2,0)$, $\bigcirc(1/2,0,1/2)$, $\bigcirc(0,1/2,1/2)$ and $\bigcirc(0,0,0)$. With respect to the primitive unit cell, the basis is $\bigcirc(0,0,0)$. Let us now consider the BCC lattice. The primitive lattice vectors are @@ -31,7 +31,7 @@ $$ \mathbf{a}_3 &= a\mathbf{\hat{y}}. \end{align} $$ -The basis of the conventional unit cell is $\bigcirc(0,0,0)$ and $\bigcirc(1,0,0)$. +The basis of the conventional unit cell is $\bigcirc(0,0,0)$ and $\bigcirc(1/2,1/2,1/2)$. For the primitive unit cell the basis is $\bigcirc(0,0,0)$. 3. @@ -77,17 +77,17 @@ $$ \mathbf{a_1} = a \hat{\mathbf{x}}, \quad \mathbf{a_2} = a \hat{\mathbf{y}}. $$ With respect to the primitive lattice vectors, the basis is -$$ -\Huge \bullet \normalsize(0,0), \quad \bigcirc(\frac{1}{2},\frac{1}{2}). -$$ +$ +\huge \bullet \normalsize(0,0), \quad \bigcirc(\frac{1}{2},\frac{1}{2}). +$ 4. The lattice is a cubic lattice. The basis of the crystal is -$$ -\Huge \bullet \normalsize = (0,0,0), \quad \bigcirc = (\frac{1}{2},\frac{1}{2},\frac{1}{2}). -$$ +$ +\huge \bullet \normalsize(0,0,0), \quad \bigcirc(\frac{1}{2},\frac{1}{2},\frac{1}{2}). +$ An example of such a material is Cesium Chloride (CsCl) @@ -106,9 +106,11 @@ $$ The conevtional unit cell of diamond consists out of two shifted fcc lattices. One set of primitive lattice vectors is $$ -\mathbf{a_1} = \frac{a}{2} \left(\hat{\mathbf{x}}+\hat{\mathbf{y}} \right) \\ -\mathbf{a_2} = \frac{a}{2} \left(\hat{\mathbf{x}}+\hat{\mathbf{z}} \right) \\ -\mathbf{a_3} = \frac{a}{2} \left(\hat{\mathbf{y}}+\hat{\mathbf{z}} \right). +\begin{align} +\mathbf{a_1} &= \frac{a}{2} \left(\hat{\mathbf{x}}+\hat{\mathbf{y}} \right) \\ +\mathbf{a_2} &= \frac{a}{2} \left(\hat{\mathbf{x}}+\hat{\mathbf{z}} \right) \\ +\mathbf{a_3} &= \frac{a}{2} \left(\hat{\mathbf{y}}+\hat{\mathbf{z}} \right). +\end{align} $$ The volume of the primitive unit cell is $$ @@ -120,7 +122,7 @@ The primitive unit cell contains 2 atoms. With respect to the set of primitive lattcie vectors, the basis is $ \mathrm{C}(0,0,0)$ and $\mathrm{C}(\frac{1}{4},\frac{1}{4},\frac{1}{4})$. 3. -One FCC lattice has 4 atoms. +One FCC lattice contains 4 atom. Because the diamond conventional unit cell contains two shifted FCC lattices, it will contain 8 atoms. The volume of the conventional unit cell is $V = a^3$.