I'm still not completely sure what you want to achieve, but it looks like you
want to optimise the inter-layer distance in a 15-layer Cu slab. As somebody
else pointed out, you might start with a thinner one and see if the result still
changes, let's say from 6 to 9 layers. Anyway, here's the procedure:
- Optimise the 3D bulk. You can do that with a primitive cell containing just
one atom, but you need a reasonable number of K-points. Increase that number
until you see no significant changes anymore.
- Create a slab from the optimised bulk structure and add a sufficient vacuum
slab in the Z direction (orthogonal to your slab). I would use Gdis for this,
but you can also do it "by hand" with a bit of trigonometry.
- Optimise the atom positions in that unit cell, keeping the cell dimensions
frozen. Your number of K-points in Z-direction should be 1. In X and Y you still
need K-points (depending on your unit cell size).
- The inter-layer distance is the difference in the Z coordinate of atoms in the
optimised structure.
Hope this helps,
Herbert
On 17/12/11 11:47, majid fathiyan wrote:
in the name of God
I am sorry for not explaining about my question, it is because of my
weakness in english,
I am working on cu(111) slab. I have 15 layer, and I want to optimize
my lattice constant. but I don`t know how to do it correctly.
I tried to change my lattice constant and calculate the total energy
and draw the diagram of lattice constant according to total energy but
the lattice constant which have the smallest total energy is so biger
that my experimental lattice constant.
so if any body knows how can I optimize my lattice constant please let me know.
thank you.
--
Herbert Fruchtl
Senior Scientific Computing Officer
School of Chemistry, School of Mathematics and Statistics
University of St Andrews
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