[Pw_forum] Lattice Constant of ESM Slab

[Minoru Otani]

Dear Robert,

There are many ways to define a lattice in input files. So I give you a general expression of the unit cell in matrix form:
2a    0           0
 0    2a          0
 0     0    10+4a+10

Please remember that, as shown in the diagram on (http://sugino.issp.u-tokyo.ac.jp/esm/index.php?SIESTA%2BESM%20Manual), L is the length of the unit cell along z-axis. Thus L=10 + 4a + 10 is correct.

Best regards,
Minoru
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Minoru Otani
National Institute of Advanced Industrial Science and Technology
Research Centre for Computational Design of Advanced Functional Materials
email : minoru.otani at aist.go.jp
tel : +81-29-861-5202
fax : +81-29-861-3171
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> On Jul 29, 2017, at 0:20, Dr. Robert Molt Jr. <r.molt.chemical.physics at gmail.com> wrote:
> 
> 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
> 
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