[Pw_forum] Is the Graphite surface flate?

Dal Corso Andrea dalcorso at sissa.it
Tue Jul 6 10:09:11 CEST 2010


On Mon, 2010-07-05 at 18:19 +0000, Masoud Nahali wrote:
> Dear Quantum Espresso users
> 
> I optimized the graphite bulk and the layers were completely flat. But
> when I try to "relax" the graphite surface (slab 2*2 with 3 monolayer)
> with 10 angstrom vacuum all the layers become extremely ripple!!! I
> can not find the problem. May it related to the number of layers?
> anyhow the number of layers is like the bulk. Your help would be a
> great gift.
> 
> input file:
> 
> &CONTROL
>   calculation  = "relax",
>   pseudo_dir   = "/home/koa/soft/qe4.2/espresso-4.2/pseudo",
>   outdir       = "/home/koa/tmp",
>   etot_conv_thr= 1.0D-4,
>   forc_conv_thr= 1.0D-3,
>   nstep=150,
>   /
> &SYSTEM
>   ibrav     = 4,
>   a         = 4.9318,
>   b         = 4.9318,
>   c         = 16.7029,
>   cosab     = -0.5,
>   cosac     = 1.0,
>   cosbc     = 1.0,
>   nat       = 24,
>   ntyp      = 1,
>   ecutwfc   = 40.D0,
>   ecutrho   = 400.D0,
>   occupations = 'smearing'
>   smearing ='mp', 
>   degauss = 0.01,
>   nspin = 2,
>   starting_magnetization(1)= 1.0,
>   /
> &ELECTRONS
>   conv_thr    = 1.D-6,
>   mixing_beta = 0.7D0,
>   diagonalization = "david",
> /
> &IONS
>  ion_dynamics="bfgs"
> /
> ATOMIC_SPECIES
> C  12.0107  C.star1s-pbe-rrkjus.UPF

Check the pseudopotential. This is a PP with a core hole for special
purposes not for standard simulations.

HTH,

Andrea


> ATOMIC_POSITIONS {angstrom}
> C    0.000000    0.000000    0.000000
> C    2.465900    0.000000    0.000000
> C    -1.232950    2.135532    0.000000
> C    1.232950    2.135532    0.000000
> C    0.000000    1.423688    0.000000
> C    -1.232950    3.559220    0.000000
> C    2.465900    1.423688    0.000000
> C    1.232950    3.559220    0.000000
> C    0.000000    0.000000    3.351450
> C    2.465900    0.000000    3.351450
> C    -1.232950    2.135532    3.351450
> C    1.232950    2.135532    3.351450
> C    1.232950    0.711844    3.351450
> C    0.000000    2.847376    3.351450
> C    3.698850    0.711844    3.351450
> C    2.465900    2.847376    3.351450
> C    0.000000    0.000000    6.702900
> C    2.465900    0.000000    6.702900
> C    -1.232950    2.135532    6.702900
> C    1.232950    2.135532    6.702900
> C    0.000000    1.423688    6.702900
> C    -1.232950    3.559220    6.702900
> C    2.465900    1.423688    6.702900
> C    1.232950    3.559220    6.702900
> K_POINTS {automatic}
> 4 4 1 1 1 1
> 
> 
> out put (optimized positions):
> 
> C        0.000000000  -0.000000000  -0.686394528
> C        2.465900000  -0.003714144  -0.758610095
> C       -1.229733457   2.137389072  -0.758610095
> C        1.229733457   2.137389072  -0.758610095
> C        0.000000000   1.427474855  -0.213813075
> C       -1.229670488   3.557326573  -0.213813075
> C        2.465900000   1.423688000  -0.285079086
> C        1.229670488   3.557326573  -0.213813075
> C       -0.000000000   0.000000000   3.630366631
> C        2.465900000  -0.014904710   3.544792504
> C       -1.220042143   2.142984355   3.544792504
> C        1.220042143   2.142984355   3.544792504
> C        1.220249305   0.704511250   3.106073641
> C        0.000000000   2.847376000   3.022325711
> C        3.711550695   0.704511250   3.106073641
> C        2.465900000   2.862041499   3.106073641
> C        0.000000000   0.000000000   7.468882932
> C        2.465900000   0.008344370   7.466151214
> C       -1.240176436   2.131359815   7.466151214
> C        1.240176436   2.131359815   7.466151214
> C        0.000000000   1.414904155   6.963129179
> C       -1.240557033   3.563611923   6.963129179
> C        2.465900000   1.423688000   6.961528237
> C        1.240557033   3.563611923   6.963129179
> 
> 
> 
> Many Thanks
> Masoud Nahali
> Sharif University of Technology
> 
> 
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-- 
Andrea Dal Corso                    Tel. 0039-040-3787428
SISSA, Via Beirut 2/4               Fax. 0039-040-3787528
34151 Trieste (Italy)               e-mail: dalcorso at sissa.it





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