As a supplement to Giuseppe’s and Lorenzo's comments:
1- forc_conv_thr should be smaller: about 1e-4 or 1e-5 (why using 1.94469e-03
with that many digits?)
2- add: etot_conv_thr= 1e-7
2- I would use ibrav=0 together with CELL-PARAMETERS (see online manual)
3- occupation=fixed, no smearing, and nbnd=number of occupied states+ a few
virtual ones. It should work as you have a dimer.
4- why using vdW corrections? not sure they are significant. Furthermore, as a
remember Grimme’s corrections are not that good for metals. I got too large
bond distances for gold (but it was for a solid)…
5- mixing_beta=0.2 should do the job and you eventually avoid oscillations in
the SCF convergence if you use a too large value (or even no convergence at
all).
6- &CELL … / section is not necessary as you only optimise atomic positions.
7- K_POINTS {Gamma} is all right as you have a molecule (k-points are only
meaningful for slabs and bulk structures)HTH, Best Pascal Boulet — Professor in computational chemistry - DEPARTMENT OF CHEMISTRY Director of the Madirel laboratory Aix-Marseille University - Avenue Escadrille Normandie Niemen - F-13013 Marseille - FRANCE Tél: +33(0)4 13 55 18 19 - Fax : +33(0)4 13 55 18 50 Email : [email protected] <mailto:[email protected]> > Le 28 janv. 2019 à 16:44, Paolo Costa <[email protected]> a écrit : > > 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) > _______________________________________________ > users mailing list > [email protected] > https://lists.quantum-espresso.org/mailman/listinfo/users
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