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

[Giuseppe Mattioli]

Dear Paolo
It's a miracle that your calculation went somewhere... ;-D
You are using a plane-wave cutoff of 1.47 Ry and a density cutoff of  
18.37 Ry. I would expect higher values, and it is always a good idea  
to test the convergence of your pseudopotentials.
As a suggestion, don't overuse scientific notation, unless you can't  
help. It generally leads to "distraction errors" such as these.
HTH
Giuseppe

Paolo Costa <paolo.costa85 at gmail.com> ha scritto:

> 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)



GIUSEPPE MATTIOLI
CNR - ISTITUTO DI STRUTTURA DELLA MATERIA
Via Salaria Km 29,300 - C.P. 10
I-00015 - Monterotondo Scalo (RM)
Mob (*preferred*) +39 373 7305625
Tel + 39 06 90672342 - Fax +39 06 90672316
E-mail: <giuseppe.mattioli at ism.cnr.it>