[Pw_forum] Dear all, can someone tell me why my force for the relax calculation get to NAN?

[文沈]

when I do a relaxation calculation for the Cr atom sit on the CuN surface.
the calculation always get the Total force as NAN
I grep the Total force from my out put file
 Total force =          NAN     Total SCF correction =     0.000851
     Total force =          NAN     Total SCF correction =     0.001184
     Total force =          NAN     Total SCF correction =     0.000620
     Total force =          NAN     Total SCF correction =     0.000731
     Total force =          NAN     Total SCF correction =     0.000699
     Total force =          NAN     Total SCF correction =     0.001291
     Total force =          NAN     Total SCF correction =     0.000744
     Total force =          NAN     Total SCF correction =     0.001344
     Total force =          NAN     Total SCF correction =     0.001741
     Total force =          NAN     Total SCF correction =     0.000733
     Total force =          NAN     Total SCF correction =     0.001029
     Total force =          NAN     Total SCF correction =     0.000619
     Total force =          NAN     Total SCF correction =     0.001437
     Total force =          NAN     Total SCF correction =     0.000516
     Total force =          NAN     Total SCF correction =     0.000703
And finally the calculation comes to an end as the error
 from bfgs : error #         1
bfgs history already reset at previous step
I read the discussion on bfgs errors, people at least get the Total force,
can anybody tell me what is the problem.
My input file is as follows

 &CONTROL
    calculation   = 'relax',
    restart_mode  = 'from_scratch',
    outdir        = './scratch1',
    PSEUDO_DIR    = './',
    verbosity     = 'high',
    wf_collect    = .t.,
    tprnfor       = .t.,
 /
 &SYSTEM
    ibrav         =  0,
    celldm(1)     =  6.95,
    nat           =  50,
    ntyp          =  3,
    ecutwfc       =  30.0d0,
    ecutrho       =  240.0d0,
    nbnd          =  280,
    occupations   =  'smearing',
    degauss       =  0.01d0,
    smearing      =  'mp',
    nspin = 2
  starting_magnetization(3)= 0.01,
    lda_plus_u=.true.  Hubbard_U(3)=4.7,
 /
 &ELECTRONS
    conv_thr     =  1.0d-7,
    mixing_mode  =  'local-TF',
    Mixing_beta  =  0.3d0,
    diagonalization = 'cg',
 /
&IONS
    upscale = 10.0d0,
/
ATOMIC_SPECIES
 Cu   63.55    Cu.pbe-d-rrkjus.UPF
 N    14.007   N.pbe-rrkjus.UPF
 Cr   51.9961   Cr.pbe-sp-van.UPF
ATOMIC_POSITIONS
Cr       0.000000000   0.500000000   1.617097960
N        0.000000000   0.033485659   1.300651193
Cu       0.000000000   0.500000000   0.914604714
Cu       0.479729230   0.010025581   1.092991536
Cu       0.509849811   0.500000000   0.484981840
Cu       0.000000000  -0.012342787   0.487244546
Cu       0.000000000   0.500000000   0.000000000
Cu       0.499999748  -0.000000018   0.000000000
Cu       0.000000000  -0.012342787  -0.487244546
Cu       0.509849811   0.500000000  -0.484981840
Cu       0.479729230   0.010025581  -1.092991536
Cu       0.000000000   0.500000000  -0.914604714
N        0.000000000   0.033485659  -1.300651193
Cr       0.000000000   0.500000000  -1.617097960
N        1.000000000  -0.001186178   1.063754946
N        0.000000000   0.966514341   1.300651193
N        1.000000000   1.001186178   1.063754946
Cu       1.000000000   0.500000000   1.032716156
Cu       0.000000000   1.500000000   1.243320618
Cu       1.000000000   1.500000000   1.039781621
Cu       1.520270770   0.010025581   1.092991536
Cu       0.479729230   0.989974419   1.092991536
Cu       1.520270770   0.989974419   1.092991536
Cu       1.490150189   0.500000000   0.484981840
Cu       0.485102831   1.500000000   0.513536013
Cu       1.514897169   1.500000000   0.513536013
Cu       1.000000000  -0.010730065   0.508502844
Cu       0.000000000   1.012342787   0.487244546
Cu       1.000000000   1.010730065   0.508502844
Cu       1.000000000   0.500000000   0.000000000
Cu       0.000000000   1.500000000   0.000000000
Cu       1.000000000   1.500000000   0.000000000
Cu       1.500000252  -0.000000018   0.000000000
Cu       0.499999748   1.000000018   0.000000000
Cu       1.500000252   1.000000018   0.000000000
Cu       1.000000000  -0.010730065  -0.508502844
Cu       0.000000000   1.012342787  -0.487244546
Cu       1.000000000   1.010730065  -0.508502844
Cu       1.490150189   0.500000000  -0.484981840
Cu       0.485102831   1.500000000  -0.513536013
Cu       1.514897169   1.500000000  -0.513536013
Cu       1.520270770   0.010025581  -1.092991536
Cu       0.479729230   0.989974419  -1.092991536
Cu       1.520270770   0.989974419  -1.092991536
Cu       1.000000000   0.500000000  -1.032716156
Cu       0.000000000   1.500000000  -1.243320618
Cu       1.000000000   1.500000000  -1.039781621
N        1.000000000  -0.001186178  -1.063754946
N        0.000000000   0.966514341  -1.300651193
N        1.000000000   1.001186178  -1.063754946
CELL_PARAMETERS
2.0 0.0 0.0
0.0 2.0 0.0
0.0 0.0 7.0
K_POINTS {automatic}
6 6 1 0 0 0Cu       1.000000000  -0.010730065  -0.508502844
Cu       0.000000000   1.012342787  -0.487244546
Cu       1.000000000   1.010730065  -0.508502844
Cu       1.490150189   0.500000000  -0.484981840
Cu       0.485102831   1.500000000  -0.513536013
Cu       1.514897169   1.500000000  -0.513536013
Cu       1.520270770   0.010025581  -1.092991536
Cu       0.479729230   0.989974419  -1.092991536
Cu       1.520270770   0.989974419  -1.092991536
Cu       1.000000000   0.500000000  -1.032716156
Cu       0.000000000   1.500000000  -1.243320618
Cu       1.000000000   1.500000000  -1.039781621
N        1.000000000  -0.001186178  -1.063754946
N        0.000000000   0.966514341  -1.300651193
N        1.000000000   1.001186178  -1.063754946
CELL_PARAMETERS
2.0 0.0 0.0
0.0 2.0 0.0
0.0 0.0 7.0
K_POINTS {automatic}
12 12 1 0 0 0
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