# Homework Help: Identifying BBravais Lattice with vectors Given

1. Jan 24, 2014

### PsychonautQQ

1. The problem statement, all variables and given/known data
Given that the primitive basis vectors of a lattice area (a/2)(I+J),(a/2)(j+k), (a/2)(k+i), where I j and k are the usual three unit vectors along Cartesian coordinates, what is the bravais lattice?

2. Relevant equations

3. The attempt at a solution
So just drawing the three vectors given gives the obvious. The first is on the z-origin and makes a 45 degree angel between the x and y axis's. The second vector is on the x-origin and makes a 45 degree angel between the y and z azis. The third vector is on the y-origin and makes a 45 degree angel between the z and x axis. How do I use these three lines to identify the type of bravais lattice?

2. Jan 26, 2014

### BruceW

It seems like you have a good idea of how to visualize the lattice vectors. That's good, although I'm not sure about your terminology. I don't know what you mean by "vector is on the x-origin"... It seems like you mean "vector is perpendicular to the x-axis". OK, anyway, you have visualized them. So, do you have a table of the properties of the different Bravais lattices? you need this so you can compare the properties of your lattice vectors to the lattice vectors of the various Bravais lattices.

3. Jan 29, 2014

### PsychonautQQ

Cool, yeah I have a table of different properties. It looks like A = B = C but i'm having trouble figuring out the angles between each vector... any tips?

4. Jan 30, 2014

### BruceW

yep, I agree, the length of each side is the same. And you are told that it is primitive lattice. So now there are only a few possible options. And yes, the next thing to do is work out the angles. If you can visualize it very well in your head, then you could work out the relationship between the angles just by thinking of it. But maybe this is a bit tricky. So, otherwise, how would you work out the angle between two vectors? And then use this method to find the three angles.

hint: think of a mathematical operation between two vectors.