[Pw_forum] rho mixing problem with PAW

[Giuseppe Mattioli]

Dear all
I'm trying to perform a bunch of calculations using the  
Ag.pbe-dn-kjpaw.UPF PP contained in the pslibrary 0.2.5 and compiled  
with the 5.0 QE version. Tests on the unit cell of Ag were fine; thus  
I was moving to the next step: a (large) Ag slab, which I had  
succesfully optimised in the past by using an USPP. After a first  
succesful scf step, with HF forces on ions reasonably low, the  
calculation (input below) stops complaining

    
%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
      Error in routine mix_rho (1):
      negative dr2
   
%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%

I've tried to mix every (reasonable) value of mixing_beta with the  
available choices of mixing_mode, but I obtain always the same error.  
As the calculations have been performed on the new fermi at cineca  
bluegene machine (still plenty of linear algebra library problems,  
cholesky errors, ... But not in this case!!!), I've tested the same  
input on a more conventional intel/mkl linux cluster, obtaining the  
same error at the same step.
Every suggestion will be appreciated...

Yours

Giuseppe


This is my inpfile

  &control
     calculation = 'relax'
     restart_mode='restart',
     prefix='ag100-k111s-dftd2',
     pseudo_dir = '/fermi/home/userexternal/gmattiol/PP_UPF/',
      
outdir='/gpfs/scratch/userexternal/gmattiol/test_qe/pw_plain/paw/././run/tmp/',
     nstep=200,
     tprnfor=.true.,
  /
  &system
     ibrav=6, celldm(1)=27.676853, celldm(3)=1.330000,
     nat= 100, ntyp= 1,
     ecutwfc = 55.0,
     occupations='smearing', degauss=0.01,
     nspin=1,
     london=.true.,
  /
  &electrons
     mixing_mode = 'plain'
     mixing_beta = 0.1
     conv_thr =  1.0d-6
     electron_maxstep = 200
  /
  &ions
     ion_dynamics='bfgs'
  /
ATOMIC_SPECIES
Ag    107.868     Ag.pbe-n-kjpaw.UPF
ATOMIC_POSITIONS {angstrom}
Ag       3.807926690  12.302649620   0.000000000    1   1   0
Ag       6.151324080  14.060198150   0.000000000    1   1   0
Ag       2.635668595   4.100351315   0.000000000    1   1   0
...

K_POINTS {automatic}
1, 1, 1, 1, 1, 1


Giuseppe Mattioli
ISM-CNR
Italy