[Pw_forum] Help regarding supercell
Duy Le
ttduyle at gmail.com
Thu Aug 4 19:13:23 CEST 2011
If ibrav=0, you must NOT specify celldm(2-6), according to the manual.
http://www.quantum-espresso.org/input-syntax/INPUT_PW.html#id3775702
More info can be found there in regarding celldm, ibrav, CELL_PARAMETTERS
PS: you should not change subject of your email. This would help to
keep your email in the same thread, and help others to understand well
your situation.
--------------------------------------------------
Duy Le
PhD Candidate
Department of Physics
University of Central Florida.
"Men don't need hand to do things"
On Thu, Aug 4, 2011 at 1:06 PM, dipak thakur <deepak.p.thakur at gmail.com> wrote:
> Sir,
>
> Good evening.
>
> I think I was unable to convey my message correctly.
>
> Kindly go through the input file below.
> ---------------------------------------------------------------------------------------------------------
> ++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++
> &CONTROL
> title = Graphene mono layer ,
> calculation = 'relax' ,
> restart_mode = 'from_scratch' ,
> outdir = '/root/tmp/' ,
> pseudo_dir = '/root/Desktop/QUANTUM_ESPRESSO/pseudo/' ,
> prefix = graphene ,
> disk_io = 'default' ,
> verbosity = 'default' ,
> etot_conv_thr = 1.D-4 ,
> forc_conv_thr = 1.D-3 ,
> nstep = 50 ,
> dt = 40 ,
> /
> &SYSTEM
> ibrav = 0,
> celldm(1) = 1.0000000,
> celldm(2) = 1.0000000,
> celldm(3) = 0.5000000,
> nat = 32,
> ntyp = 1,
> ecutwfc = 50 ,
> ecutrho = 400 ,
> occupations = 'smearing' ,
> smearing = 'methfessel-paxton' ,
> nspin = 1 ,
> lda_plus_u = .false. ,
> /
> &ELECTRONS
> electron_maxstep = 300,
> conv_thr = 1.0d-8 ,
> mixing_mode = 'plain' ,
> mixing_beta = 0.5 ,
> diagonalization = 'cg' ,
> diago_cg_maxiter = 50,
> /
> &IONS
> /
> CELL_PARAMETERS
> 16.121319540 9.383047808 0.000000000
> 0.000000000 18.658162370 0.000000000
> 0.000000000 0.000000000 56.689342400
> ATOMIC_SPECIES
> C 12.01070 C.pbe-van_bm.UPF
> ATOMIC_POSITIONS angstrom
> C 2.891630000 7.402190000 2.000000000
> C 3.592920000 8.638320000 2.000000000
> C 3.603490000 6.167020000 2.000000000
> C 5.018600000 8.645010000 2.000000000
> C 5.021500000 6.165980000 2.000000000
> C 5.733020000 7.405220000 2.000000000
> C 1.471840000 7.396160000 2.000000000
> C 2.891120000 9.870660000 2.000000000
> C 2.894710000 4.932640000 2.000000000
> C 5.733190000 9.888500000 2.000000000
> C 5.736430000 4.941300000 2.000000000
> C 7.163480000 7.412030000 2.000000000
> C 1.474740000 4.926900000 2.000000000
> C 0.762281000 8.627830000 2.000000000
> C 0.763134000 6.161720000 2.000000000
> C 1.471500000 9.863350000 2.000000000
> C 3.603410000 11.109500000 2.000000000
> C 5.021240000 11.123900000 2.000000000
> C 3.605120000 3.701560000 2.000000000
> C 5.026450000 3.707890000 2.000000000
> C 7.878070000 8.655320000 2.000000000
> C 7.163730000 9.894970000 2.000000000
> C 7.162030000 4.948140000 2.000000000
> C 7.876190000 6.176770000 2.000000000
> C 5.736340000 12.352200000 2.000000000
> C 0.772689000 3.691020000 2.000000000
> C 0.762793000 1.220030000 2.000000000
> C 7.876450000 11.133700000 2.000000000
> C 7.162030000 12.358700000 2.000000000
> C 7.872010000 13.592200000 2.000000000
> C 2.894790000 2.466190000 2.000000000
> C 1.474820000 2.458780000 2.000000000
> K_POINTS automatic
> 6 6 1 1 1 1
>
> ---------------------------------------------------------------------------------------------------------
> ++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++
>
> I am desparately trying to understand how to determine:
> 1. The
> CELL_PARAMETERS
> 16.121319540 9.383047808 0.000000000
> 0.000000000 18.658162370 0.000000000
> 0.000000000 0.000000000 56.689342400
> (or how are they determined in this case) - This is again a copy of earlier
> post.
> 2. The celldm(1) = 1.0000000,
> celldm(2) = 1.0000000,
> celldm(3) = 0.5000000,
> How do I fix them.
> Is there any software and/or technique to do this? or Is there any
> mathematical relation that would be able to provide me these values.
> The cell parameters are given to a precision upto 9th decimal place.
>
> Secondly, the celldm(3) =0.5, does it mean that it would divide the value
> 56.689342400 by 2 and can similar logic be applied to celldm(1) and
> celldm(2)?
> Thirdly, if I view the geometry in XcrySDen, it show vacuum layers in Z
> direction, but no gap/vacuum in x and y direction? I have seen this in many
> papers published till date and is trying to understand these things.
> Doesn't the adjacent supercell (in x and y direction) interact with the
> supercell under consideration?
> Also is there relation between the co-ordinates of the atom, the CELL
> PARAMETERS and celldm()?
>
> I hereby request you to kindly help me in this regard.
>
> Deepak Thakur
> Research Student
> Swami Ramanand Teerth Marathwada University,
> Vishnupuri, Nanded,
> Maharashtra,
> India.
>
> _______________________________________________
> Pw_forum mailing list
> Pw_forum at pwscf.org
> http://www.democritos.it/mailman/listinfo/pw_forum
>
>
More information about the users
mailing list