[Pw_forum] NEB calcualtion - Problem

[PRASENJIT GHOSH]

What is your problem?
If ur problem is that the forces are zero then that's fine. You have set
nstep=0 and hence the code doesn't do any iterations. It will only
generate the path. This is generally done to check whether the initial
guess of the path generated by the code is reasonable or not.

Prasenjit.

On Wed, August 30, 2006 3:36, Krishnan  Sridevi said:
> Dear all,
>
> I try to run NEB calculation, but I have a problem.
> I have compiled the serial version on an P4 system. i could run the
> examples. I did a check example and was right till example 4.
>
> This is the input file:
> &CONTROL
>                  calculation = 'neb' ,
>                 restart_mode = 'restart' ,
>                       outdir =
> '/home/Sridevi/Downloads/espresso-3.1.1/juanma/temp/'
> ,
>                   pseudo_dir =
> '/home/Sridevi/Downloads/espresso-3.1.1/pseudo/' ,
>                       prefix = 'CH4O2_CH4OOH' ,
>                        nstep = 0 ,
>  /
>  &SYSTEM
>                        ibrav = 0,
>                    celldm(1) = 1.D0,
>                          nat = 7,
>                         ntyp = 3,
>                   tot_charge = 1,
>                      ecutwfc = 20.0D0 ,
>                      ecutrho = 100.0D0 ,
>                  occupations = 'smearing' ,
>                      degauss = 0.03D0 ,
>                        nspin = 2 ,
>    starting_magnetization(1) = 0.5D0,
>  /
>  &ELECTRONS
>                     conv_thr = 1.D-8 ,
>                  mixing_beta = 0.3D0 ,
>  /
>  &IONS
>            pot_extrapolation = 'second_order' ,
>            wfc_extrapolation = 'second_order' ,
>                num_of_images = 8 ,
>                   opt_scheme = 'broyden' ,
>                           ds = 2.D0 ,
>                     path_thr = 0.1D0 ,
>                    CI_scheme = 'manual' ,
>                        k_max = 0.3D0 ,
>                        k_min = 0.2D0 ,
>  /
> CELL_PARAMETERS { cubic }
>     12.000000000    0.000000000    0.000000000
>      0.000000000    5.000000000    0.000000000
>      0.000000000    0.000000000    5.000000000
> ATOMIC_SPECIES
>     H    1.00794   HUSPBE.RRKJ3
>     C   12.005852  C.pbe-rrkjus.UPF
>     O   16.002714  O.pbe-rrkjus.UPF
> ATOMIC_POSITIONS { bohr }
> first_image
>     C       1.954897    -0.064367     0.000191  0 0 0
>     H       3.028255    -0.250143    -0.002686  1 1 1
>     H       1.802200     1.016517    -0.048979  1 1 1
>     H       1.533716    -0.563048    -0.877534  1 1 1
>     H       1.551082    -0.478320     0.928585  1 1 1
>     O      -0.820010     0.362853    -0.000173  1 1 1
>     O      -1.635569    -0.280204     0.000107  1 1 1
> last_image
>     C      -1.161432    0.181714     0.000017
>     H      -0.969529    1.258642    -0.003615
>     H      -1.675000   -0.151640    -0.902206
>     H      -1.672119   -0.146187     0.905885
>     H       0.960800    1.122493    -0.000061
>     O       0.114715   -0.546742    -0.000042
>     O       1.175840    0.150042     0.000028
>
> K_POINTS gamma
> CLIMBING_IMAGES
> 5
>
> and the output file is the following:
>
>  Program PWSCF     v.3.1.1  starts ...
>      Today is 29Aug2006 at 18: 1:23
>
>      Ultrasoft (Vanderbilt) Pseudopotentials
>
>      Current dimensions of program pwscf are:
>
>      ntypx = 10   npk = 40000  lmax =  3
>      nchix =  6  ndmx =  2000  nbrx = 14  nqfx =  8
>
>      RRKJ3 Ultrasoft PP for H
>
>
>      gamma-point specific algorithms are used
>
>
>      initial path length           =  8.3312 bohr
>      initial inter-image distance  =  1.1902 bohr
>
>      calculation                   =  neb
>      restart_mode                  =  from_scratch
>      opt_scheme                    =  broyden
>      num_of_images                 =  8
>      nstep                         =  0
>      CI_scheme                     =  manual
>     first_last_opt                =  F
>      coarse-grained phase-space    =  F
>      use_freezing                  =  F
>      ds                            =  2.0000 a.u.
>      k_max                         =  0.3000 a.u.
>      k_min                         =  0.2000 a.u.
>      suggested k_max               =  0.1542 a.u.
>      suggested k_min               =  0.1028 a.u.
>      path_thr                      =  0.1000 eV / A
>
>      list of climbing images :   5,
>
>      activation energy (->) =   0.000000 eV
>      activation energy (<-) =   0.000000 eV
>
>      image        energy (eV)        error (eV/A)        frozen
>
>          1          0.0000000            0.000000            F
>          2          0.0000000            0.000000            F
>          3          0.0000000            0.000000            F
>          4          0.0000000            0.000000            F
>          5          0.0000000            0.000000            F
>          6          0.0000000            0.000000            F
>          7          0.0000000            0.000000            F
>          8          0.0000000            0.000000            F
>
>   path length          =  8.331 bohr
>      inter-image distance =  1.190 bohr
>
>      PWSCF        :     0.08s CPU time
>
>
>
>
>
>
>
>      General routines
>
> Please help.
>
>
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PRASENJIT GHOSH,
Ph. D STUDENT,
THEORETICAL SCIENCES UNIT,
JAWAHARLAL NEHRU CENTRE,
JAKKUR P. O.,
BANGALORE - 560064,
INDIA.

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