[Pw_forum] gold surfaces & convergence

[Patricia Paredes]

Hi, I'am doing calculations on surface systems. I want to calculate some
adsorbates on gold 111 surfaces, but i have convergence troubles with the
gold slab. I know from the cluster HF calculations that metals, and in
particular gold, is a difficult case. I'd already made some PWSCF
calculations with cooper, and didn't have any problem.
One of my inputs file is the following...

tricapa de Au
Au
 &control
    calculation='scf'
    restart_mode='from_scratch',
    prefix='Au1',
    pseudo_dir = '/home/pwscf/pseudo/',
    outdir='/home/patricia/mma/oro/temp/'
 /
 &system
    ibrav=0,
    nat=12,
    ntyp=1,
    ecutwfc = 22.0,
    ecutrho = 180.0
    celldm(1)=9.56
    degauss=0.03
 /
 &electrons
    mixing_ndim     =  20
    mixing_mode     =  'local-TF'
    conv_thr        =  1.0d-10
    mixing_beta     =  0.25
    diagonalization =  'diis'
 /
ATOMIC_SPECIES
Au 79   Au_pbe-d-van.UPF
ATOMIC_POSITIONS {alat}
Au    0.0000000      0.0000000      0.0000000
Au    0.5773502      0.0000000      0.0000000
Au    1.1547005      0.0000000      0.0000000
Au    0.2886751      0.1666667     -0.4714045
Au    0.8660254      0.1666667     -0.4714045
Au    0.5773502     -0.3333334     -0.4714045
Au    0.5773502      0.3333334     -0.9428090
Au    0.2886751     -0.1666667     -0.9428090
Au    0.8660254     -0.1666667     -0.9428090
Au    0.0000000      0.0000000     -1.4142135
Au    0.5773502      0.0000000     -1.4142135
Au    1.1547005      0.0000000     -1.4142135
CELL_PARAMETERS {cubic}
 0.8660254  0.5   0.0
 0.8660254 -0.5   0.0
 0.0000000  0.0   4.0
K_POINTS {automatic}
4   4   1  0  0  0




Can someone gime me some hints to converge this kind of calculations?
Thank you!!
Patricia.