[QE-users] Wrong prediction for Pd-Pd bond length

[Paolo Costa]

Dear QE users,

I am trying to optimize (relax) Pd dimer (Pd2) as cluster placed on cubic
lattice.
However I got a value of Pd-Pd bond length which is far too long (3.36 A)
compare to the experimental one (about 2.6 A).
Am I doing something wrong? Here below the input file:

&CONTROL
     calculation   = "relax"
prefix ='Pd2'
    forc_conv_thr =  1.94469e-03
    max_seconds   =  1.34369e+14
    nstep         = 800
    pseudo_dir    = "/home/pcosta/pseudo"
verbosity     ='high'
disk_io ='none'
    tprnfor       = .TRUE.
    tstress       = .TRUE.
/

&SYSTEM
    a     =  4.50000e+01
    degauss                   =  1.00000e-02
    ecutrho                   =  1.83747e+01
    ecutwfc                   =  1.46997e+00
lda_plus_u                = .FALSE.
    ibrav                     = 1
    nat                       = 2
    nspin                     = 2
    ntyp                      = 1
    occupations               = "smearing"
    smearing                  = "gaussian"
    starting_magnetization(1) =  2.00000e-01
    assume_isolated = 'makov-payne'
vdw_corr                  = 'grimme-d3'
/

&ELECTRONS
    conv_thr         =  1.00000e-08
    diagonalization  = "david"
    electron_maxstep = 800
    mixing_beta      =  4.00000e-01
    startingpot      = "atomic"
    startingwfc      = "atomic+random"
/

&IONS
    ion_dynamics = "bfgs"
trust_radius_min=1e-5
/

&CELL
    cell_dofree    = "all"
    cell_dynamics  = "bfgs"
    press_conv_thr =  5.00000e-01
/

K_POINTS {automatic}
 3  3  1  0 0 0

ATOMIC_SPECIES
Pd    106.42000  Pd.pbe-n-kjpaw_psl.1.0.0.UPF

ATOMIC_POSITIONS {angstrom}
Pd     16.194860  19.259990  18.659720
Pd     18.251640  18.665930  18.594650

Thanks.
-- 
Paolo Costa, Ph.D.
Postdoctoral Researcher
Department of Chemistry and Biomolecular Sciences
University of Ottawa
10 Marie Curie, Ottawa, ON K1N 6N5, Canada
Room number: DRO 326 (D'Iorio Hall)
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