[Pw_forum] Transition state calculation error

Cecil Humphrey Botchway humphrey2g4 at gmail.com
Tue May 3 14:48:02 CEST 2016

Hi There,
I am trying to run a transition state calculation using neb.x with methanol
C-OH bond breaking in the zeolite micro pore (the system is composed of 120
atoms). I have tried relaxing the whole structure with the adsorbate and
freezing only the zeolite leaving the adsorbate. I have even tried
increasing and decreasing the numbers of processor cores from 8-16. I
encounter the same error (which is below) regardless .

     task #         0
     from rdiaghg : error #       818
     S matrix not positive definite

What could be the possible cause?
This is how my input looks like

  restart_mode      = 'from_scratch'
  string_method     = 'neb',
  nstep_path        = 20,
  ds                = 2.D0,
  opt_scheme        = "broyden",
  num_of_images     = 7,
  k_max             = 0.3D0,
  k_min             = 0.2D0,
  CI_scheme         = "auto",
  path_thr          = 0.1D0,
  prefix         = "TS1"
  outdir         = "./tmp/",
  pseudo_dir     = "/home/cbotchway/Cecil",
  ibrav                  = 0,
  nat                    = 120,
  ntyp                   = 5,
  ecutwfc                = 40.0D0,
  ecutrho                = 240.0D0,
  nspin                  = 2,
  starting_magnetization = 0.5D0,
  occupations            = "smearing",
  degauss                = 0.03D0,
  conv_thr    = 1.D-6,
  mixing_beta = 0.2D0,
  electron_maxstep =1000000,
O    15.99940    O.pbe-van_ak.UPF
Si   28.0855    Si.pbe-n-van.UPF
Al   26.98154   Al.pbe-n-van.UPF
H     1.00794    H.pbe-van_ak.UPF
C    12.0107     C.pbe-van_ak.UPF

Attached to this post is a copy of my input file
Any help or advice would be appreciated
Thank you in advance
Cecil Huymphrey Botchway
Mphil. Material Science and Computational Chemistry
Department of Chemistry
Kwame Nkrumah University of Science and Technology
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