[QE-users] Energy corrections for adsorption study of hydrogen molecule

[‍강동우[학생](대학원 화학공학과)]

Dear all QE users,

I'm now calculating adsorption energy of a hydrogen molecule on cobalt
(0001) surface.

I referred some papers: Yu et al, Int J Hydrog Energy, 2018, and Helden et
al, ACS catalysis, 2012

They reported results of dissociative adsorption of H2 molecule to top site
about ~-0.2 eV, and fcc hollow site about ~-1 eV.

But in my calculation, I have some different results in both cases, -0.4 eV
and -1.2 eV.

Although I used different method and basis set (PBE, PAW), I think that the
difference about 0.2 eV for each case are quite large just considered as a
simple error from using different method and basis sets.

Other settings are almost same(kinetic energy cutoff, smearing,
spin-polarized, etc).

I did not include zero point energy correction, but it seems that ZPE
correction is not large for this case.

This is my input script (adsorbed state)

---------------------------------------------------------------------------------------

&CONTROL
    title = 'Co_da'
    calculation = "relax"
    restart_mode = 'from_scratch',
    tprnfor = .TRUE.,
    prefix =  'Co_da'
    max_seconds =  432000
    pseudo_dir = './'
    outdir =  './work'
    disk_io = 'low'
    wf_collect = .TRUE.
/
&SYSTEM
    a                         =  7.47797
    b                         =  7.47797
    c                         =  38.06076
    cosab                     =  5.00000e-01
    degauss                   =  1.46997e-02
    ecutrho                   =  2.94E000+02
    ecutwfc                   =  3.67493e+01
    ibrav                     = 12
    nat                       = 38
    nspin                     = 2
    ntyp                      = 2
    occupations               = "smearing"
    nosym                     = .TRUE.
    smearing                  = "methfessel-paxton"
    starting_magnetization (1)    = 2.00000e-1
    starting_magnetization (2)    = 2.00000e-1
/
&ELECTRONS
    conv_thr         =  1.00000e-06
    electron_maxstep = 600
    mixing_beta      =  3.00000e-01
    mixing_mode      = "local-TF"
    startingpot      = "atomic"
    startingwfc      = "atomic+random"
/
&ions
/
&cell
/

K_POINTS {automatic}
 6  6  1  0 0 0

ATOMIC_SPECIES
Co     58.93320  Co.pbe-n-kjpaw_psl.1.0.0.UPF
H       1.00794  H.pbe-kjpaw_psl.1.0.0.UPF

ATOMIC_POSITIONS {angstrom}
~~~~~
---------------------------------------------------------------------------------------
Can anyone recommend some advice for me to correct this error?

Thanks in advance.

Dongwoo Kang
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