[Pw_forum] Lattice Constant of ESM Slab

[Dr. Robert Molt Jr.]

Good afternoon,

I do not understand how the lattice constant is defined in an ESM 
calculation of a slab.

Let's say I have a 2x2x4 slab, and wish to simulate a vacuum on either 
side of it. Let us say the unit cells are simple cubic, such that the 
height is "a". For a 10 Angstrom vacuum, I assume L/2=10, pursuant to 
the diagram on 
(http://sugino.issp.u-tokyo.ac.jp/esm/index.php?SIESTA%2BESM%20Manual). 
If I do

assume_isolated=esm

esm_bc=bc1

Is the lattice constant for this situation defined as

celldm(1)= L/2 + 4a + L/2

?

Dr. Robert Molt

Indiana University Perdue University