[Pw_forum] NEB Calculation with Ti and Graphene

[Ettore Baldini Neto]

Dear users,

I'm playing with a NEB calculation involving one Ti atom in a graphene monolayer.
The calculation crashes due to diagonalization problems according to the message below.
*******************************************
   task #         8
     from cdiaghg : error #       434
     diagonalization (ZHEGV*) failed
********************************************

In what follows I copied my input file (without the atomic positions in order to make it small for the readers)
Any hint? Am I doing something very wrong? 
I'm not using for now polarization for Ti for now in order to make things simpler. I'm planning to include it soon.
Also, I'm using a large ecut but I figured out that for graphene and for this pseudo 35-40Ry might work fine.

title = 'Graphene mono layer'
   calculation =   "neb"   ,
   restart_mode = 'from_scratch' ,
   outdir='/home/usuarios/baldini/espresso-4.2.1/tmp/' ,
   pseudo_dir = '/home/usuarios/baldini/espresso-4.2.1/pseudo' ,
               etot_conv_thr = 1.0E-3  ,
               forc_conv_thr = 1.0D-4 ,
               nstep=10,
               prefix='1MLG_Ti_NEB',
 /
 &SYSTEM
                       ibrav = 0.,
                       ntyp = 2 ,
                       nat = 33 ,
                       ecutwfc = 50.0 ,
                       ecutrho = 400.0,
                       occupations = 'smearing' ,
                       degauss = 0.02,
                       smearing = 'mv' ,
/
 &ELECTRONS
             conv_thr  =  1.0d-7  ,
             mixing_beta = 0.4 ,
/
 &IONS
  num_of_images     = 4,
  opt_scheme        = "broyden",
  path_thr          = 0.03D0,
/
ATOMIC_SPECIES
C   12.0107   C.pbe-van_ak.UPF
Ti  47.8670   Ti.pbe-sp-van_ak.UPF
CELL_PARAMETERS
16.12131954   9.383047808   0.0000000
 0.00000000  18.658162370   0.0000000
 0.0000000    0.000000000  56.6893424
ATOMIC_POSITIONS  angstrom 
 first_image
...
last image
.......
K_POINTS {automatic} 
6.0 6.0 1.0 1.0 1.0 1.0


Thanks a lot and best regards

************************************************************************
Dr. Ettore Baldini-Neto,
Researcher at Wernher von Braun Center of Advanced Research 
Campinas, Brazil
***********************************************************************