[Pw_forum] BFGS Relaxation

[ashkan shekaari]

Dear kanak
Ecutwfc is too small. Find the optimal value. Set ecutrho = 5*ecutwfc.
Set mixing mode local TF because of inhomogenity.
Set conv thr of order 10^-9set dt= 20

Kind regards
Ashkan Shekaari
Tell: +98 933 459 7122; +98 921 346 7384
On Jul 25, 2015 5:59 PM, "Kanak Datta" <kanakeee08 at gmail.com> wrote:

> Dear researchers
>
> For BFGS relaxation of bilayer WS2..I have been using the following code...
> &CONTROL
>       calculation = 'relax',
>      restart_mode = 'from_scratch',
>            outdir = 'D:\QuantumEspresso\Quantum ESPRESSO 64-bit
> 5.1.2-mpich2\WS2Bilayer\outdir',
>            prefix = 'WS2Bilayer',
> /
> &SYSTEM
>  ibrav = 0,
> a = 1.86,
> nat = 6,
> ntyp = 2,
> occupations = 'smearing',
> smearing = 'methfessel-paxton',
> degauss = 0.001,
> nspin=2,
> ecutwfc = 20,
> ecutrho = 160,
> nbnd = 30,
> starting_magnetization=0.6,
>  /
>
> &ELECTRONS
> conv_thr = 1.0d-5,
> mixing_mode = 'plain',
> mixing_beta = 0.7,
> diagonalization = 'david',
> diago_full_acc = .true.
>  /
> &IONS
> ion_dynamics      = 'bfgs',
> pot_extrapolation = 'second_order',
> wfc_extrapolation = 'second_order',
> upscale           = 100,
> /
> CELL_PARAMETERS
> 1.5 0.8660254038 0.00000
> 1.5 -0.8660254038 0.00000
> 0.0000 0.00000 15.0
> ATOMIC_SPECIES
> W 183.84 W.pbe-hgh.UPF
> S 32.066 S.pbe-hgh.UPF
> ATOMIC_POSITIONS (angstrom)
> S       0.000000000  0.000000000   5.15
> S       0.000000000  0.000000000   2
> W       1.818653348  0.000000000   3.575
> S       0.000000000  0.000000000   8.6
> S       0.000000000  0.000000000   10.175
> W       1.818653348  0.000000000   11.75
> K_POINTS {automatic}
> 24 24 1   0 0 0
>
>
> 1. I just wanted to know whether the cutoff values are ok or not.......As
> I am from EEE background..I have very little knowledge on these things.....
> 2. Besides should the van der waals corrections be applied in relaxation
> part from the beginning?
>
> Thanks in advance.
>
> Sincerely yours
> kanak
> BUET
>
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