# We have that for a crystal the lattice parameters

1. Dec 1, 2011

### Eduard1

1. The problem statement, all variables and given/known data

We have that for a crystal the lattice parameters (in angstrom and degree) are:

a b c (in Angstrom)
10.5 10.5 10.5

$\alpha$ β γ (in degree)
109.5 109.5 109.5

Find the lattice vectors components.

2. Relevant equations

3. The attempt at a solution

The way I solved the problem:

a_1 (first component of the vector a) = 0
a_2 = sin (109.5) * 10.5 = 9.8977356555
a_3 = cos (109.5) * 10.5 = -3.5049720195

b_1 = sin (109.5) * 10.5 = 9.8977356555
b_2 = 0
b_3 = cos (109.5) * 10.5 = -3.5049720195

c_1 = sin (109.5) * 10.5 = 9.8977356555
c_2 = cos (109.5) * 10.5 = -3.5049720195
c_3 = 0

The matrix with the vectors' components is then:

0.0000000000 9.8977356555 -3.5049720195
9.8977356555 0.0000000000 -3.5049720195
9.8977356555 -3.5049720195 0.0000000000

Is this correct ?

One could also write this matrix as:

0.0000000000 -3.5049720195 9.8977356555
9.8977356555 0.0000000000 -3.5049720195
9.8977356555 -3.5049720195 0.0000000000

(notice the interchange in the the first vector components). Which matrix is correct ? The ordering will be definitelly important for the atom positions.

Thank you very much for any help.
Eduard
1. The problem statement, all variables and given/known data

2. Relevant equations

3. The attempt at a solution

2. Dec 5, 2011

### ehild

Re: Vectors

Check if those vectors really enclose 109.5° angle.

ehild