[Pw_forum] scan the lattice constant

[Eyvaz Isaev]

Hi, 

Presumably, you should use more k-points, and may be
larger cutof energy. More accurate calculations
(conv_thr) also might help.

Bests,
Eyvaz

--- XunLei Ding <dxl at ustc.edu.cn> wrote:

> Dear all,
> I do a calculation to get the lattice constant of Ni
> crystal.
> I scan the lattice constant from 6.60 to 6.70 a.u.
> using the bash file below.
> The experimental value is 6.66 and is consistent
> with my result.
> But it is clear that the curve departs into two
> parts at 6.66. 
> (see the picture at
> http://www.bsc.ustc.edu.cn/~dxl/download/Graph1.JPG)
> Would you tell my why and how to solve this problem.
> 
> Thank you!
> 
> Ding Xunlei
> 
> for a0 in  6.60 6.61 6.62 6.63 6.64 6.65 6.66 6.67
> 6.68 6.69 6.70
> do
> cat >test.in<<!
> &control
>     calculation='scf'
>     restart_mode='from_scratch',
>     pseudo_dir = '/home/bsc/dxl/pseudo/',
>     outdir='./'
>     prefix='zz'
>     tprnfor = .true.,
> for a0 in  6.64
> do
> cat >test.in<<!
> &control
>     calculation='scf'
> for a0 in  6.65
> do
> cat >test.in<<!
> &control
>     calculation='scf'
>     restart_mode='from_scratch',
>     pseudo_dir = '/home/bsc/dxl/pseudo/',
>     outdir='./'
>     prefix='zz'
>     tprnfor = .true.,
>     tstress = .true.
>  /
>  &system
>     ibrav=2, celldm(1) =$a0
>     nat=1,ntyp=1,
>     nspin = 2,  starting_magnetization(1)=0.7,
>     ecutwfc = 24.0, ecutrho = 288.0,
>     occupations='smearing',
> smearing='methfessel-paxton', degauss=0.01
>  /
>  &electrons
>     electron_maxstep= 200
>     diagonalization=''
>     conv_thr = 1.0e-8
>     mixing_beta = 0.2
>  &cell
>     cell_dynamics = 'none'
>     cell_factor = 1.2
>  /
>  &ions
>      ion_dynamics = 'damp'
> 
>  /
> ATOMIC_SPECIES
>  Ni 58.69 Ni.pbe-nd-rrkjus.UPF
> ATOMIC_POSITIONS
>  Ni       0.00000000   0.000000000   0.000000000  1
> 1 1
> K_POINTS (automatic)
> 13 13 13 1 1 1
> !
> 
> 
> 
> 
> 
> _______________________________________________
> Pw_forum mailing list
> Pw_forum at pwscf.org
> http://www.democritos.it/mailman/listinfo/pw_forum
> 



	
		
______________________________________________________
Click here to donate to the Hurricane Katrina relief effort.
http://store.yahoo.com/redcross-donate3/