[QE-users] K-point in neb.x

Antoine Jay ajay at laas.fr
Wed Mar 24 08:58:55 CET 2021


Dear Clarence,
An energy barrier should represent a local event, ie, not periodically repeted.
For these reason, the Kpoint mesh should not affect the energy barrier.
I conclude from your results that you have long range interactions and that your supercell is  too small along xy to represent an isolated Li.

Regards,

Antoine Jay
LAAS-CNRS
Toulouse, France

Le Mercredi, Mars 24, 2021 03:52 CET, LEUNG Clarence <liangxy123 at hotmail.com> a écrit:
  
Dear QE users,

 
Recently, I study on the Li ion diffusion on 2D layer surface. And I found that the K-point in neb.x significantly affects the barrier. The following figure is 5*5*1, 9*9*1 and 13*13*1,

 



 
Except point, all set are fixed as follows:

 
BEGIN
BEGIN_PATH_INPUT
&PATH
  restart_mode = 'from_scratch'
  string_method = 'neb',
  nstep_path = 500,
  ds = 1.D0,
  opt_scheme = "broyden",
  num_of_images = 10,
  CI_scheme = "no-CI",
  path_thr = 0.05D0,
/
END_PATH_INPUT
BEGIN_ENGINE_INPUT
&CONTROL
  nstep = 200 ,
  wf_collect = .true. ,
  verbosity='low',
  max_seconds = 320000 ,
  etot_conv_thr = 3.7D-7 ,
  forc_conv_thr = 4.0D-4 ,
/
&SYSTEM
  ibrav=4,
  celldm(1)=16.8205089265d0, celldm(3)=2.8086637164d0,
  nat=28,
  ntyp=3,
  ecutwfc=60,
  ecutrho=600,
  input_dft='PBE',
  occupations='smearing',
  smearing = 'gaussian' ,
  degauss = 0.01 ,
  nspin = 2 ,
  starting_magnetization(1) = 0.5 ,
  vdw_corr = 'DFT-D3' ,
/
&ELECTRONS
  conv_thr=1d-07,
  mixing_beta=0.7d0,
  mixing_mode ='local-TF',
  electron_maxstep = 500 ,
/
&IONS
/
ATOMIC_SPECIES
  Li 6.941000d0 Li.pbe-sl-kjpaw_psl.1.0.0.UPF
  N 14.006700d0 N.pbe-n-kjpaw_psl.1.0.0.UPF
  Ti 47.867000d0 Ti.pbe-spn-kjpaw_psl.1.0.0.UPF
K_POINTS {automatic}
  1 1 1 0 0 0
BEGIN_POSITIONS
FIRST_IMAGE
ATOMIC_POSITIONS {crystal}
Ti            0.7770490991        0.2207650450        0.4526649491
Ti            0.8912354588        0.1122845729        0.5447173889
N             0.6666667383        0.0000000000        0.4995961962
Ti            0.7780555528        0.5556941072        0.4517577041
Ti            0.8890435897        0.4447534785        0.5440905933
N             0.6673919617        0.3329974904        0.4979423184
Ti            0.7770488498        0.8896175800        0.4526648274
Ti            0.8890434165        0.7776226563        0.5440907450
N             0.6673920333        0.6677278762        0.4979422530
Ti            0.1088705771        0.2211023009        0.4510416620
Ti            0.2233051542        0.1132758120        0.5420585003
N            -0.0010611379       -0.0007252950        0.4979422530
Ti            0.1109726480        0.5556945774        0.4517577341
Ti            0.2233049049        0.4433625308        0.5420583786
N            -0.0010611379        0.3329974188        0.4979422530
Ti            0.1109728212        0.8886111263        0.4517575824
Ti            0.2219134870        0.7776229056        0.5440906233
N             0.0000000000        0.6666667383        0.4979808302
Ti            0.4455657413        0.2211020516        0.4510417837
Ti            0.5543824685        0.1122843997        0.5447172372
N             0.3336691046       -0.0007252950        0.4979422530
Ti            0.4455652711        0.5577968215        0.4510418137
Ti            0.5533912294        0.4433620606        0.5420583486
N             0.3333332617        0.3333332617        0.4956870765
Ti            0.4459022777        0.8896177532        0.4526649791
Ti            0.5543819983        0.7754308633        0.5447172672
N             0.3336691762        0.6677278046        0.4979421876
Li            0.3333330289        0.3333338479        0.6400903690
INTERMEDIATE_IMAGE
ATOMIC_POSITIONS {crystal}
Ti            0.7789152822        0.2220836302        0.4501659003
Ti            0.8888446372        0.1110228518        0.5426653048
N             0.6673156201       -0.0006488818        0.4964052852
Ti            0.7789152822        0.5568316396        0.4501659003
Ti            0.8867836243        0.4433916373        0.5427300585
N             0.6675598953        0.3337799476        0.4952771792
Ti            0.7777776240        0.8888888058        0.4505257421
Ti            0.8888446372        0.7778214356        0.5426653048
N             0.6673156201        0.6679645019        0.4964052852
Ti            0.1098352888        0.2220838795        0.4501657786
Ti            0.2237552464        0.1118774483        0.5405467345
N            -0.0012977636       -0.0006488818        0.4964052852
Ti            0.1111114878        0.5555557376        0.4510371855
Ti            0.2232753282        0.4433921075        0.5427300885
N             0.0001334406        0.3336001430        0.4969839949
Ti            0.1098352888        0.8877513969        0.4501657786
Ti            0.2232753282        0.7798828710        0.5427300885
N             0.0001334406        0.6665332977        0.4969839949
Ti            0.4444451994        0.2222225935        0.4488650365
Ti            0.5547895931        0.1118772751        0.5405465828
N             0.3328866474       -0.0008932286        0.4952771138
Ti            0.4445836925        0.5568321098        0.4501659303
Ti            0.5547895931        0.4429119684        0.5405465828
N             0.3328866474        0.3337798760        0.4952771138
Ti            0.4445836925        0.8877515701        0.4501659303
Ti            0.5556437194        0.7778216849        0.5426651831
N             0.3330664520        0.6665332261        0.4969839295
Li            0.4444459557        0.2222229977        0.6387918156
LAST_IMAGE
ATOMIC_POSITIONS {crystal}
Ti            0.7788993600        0.2211011068        0.4510426589
Ti            0.8877157525        0.1122843572        0.5447186005
N             0.6670022049       -0.0007257761        0.4979412162
Ti            0.7788993600        0.5577982408        0.4510426589
Ti            0.8867240759        0.4433618631        0.5420585485
N             0.6666666667        0.3333333333        0.4956851811
Ti            0.7792359152        0.8896179514        0.4526660159
Ti            0.8877157525        0.7754310455        0.5447186005
N             0.6670022049        0.6677279810        0.4979412162
Ti            0.1103825154        0.2207645516        0.4526660159
Ti            0.2245690642        0.1122843572        0.5447186005
N             0.0000000000        0.0000000000        0.4995954192
Ti            0.1113906330        0.5556953102        0.4517586619
Ti            0.2223762417        0.4447520239        0.5440918698
N             0.0007257761        0.3329977951        0.4979412162
Ti            0.1103825154        0.8896179514        0.4526660159
Ti            0.2223762417        0.7776238680        0.5440918698
N             0.0007257761        0.6677279810        0.4979412162
Ti            0.4422022260        0.2211011068        0.4510426589
Ti            0.5566382465        0.1132760338        0.5420585485
N             0.3322720190       -0.0007257761        0.4979412162
Ti            0.4443051566        0.5556953102        0.4517586619
Ti            0.5566382465        0.4433618631        0.5420585485
N             0.3322720190        0.3329977951        0.4979412162
Ti            0.4443051566        0.8886098338        0.4517586619
Ti            0.5552480857        0.7776238680        0.5440918698
N             0.3333333333        0.6666666667        0.4979808492
Li            0.6666674857        0.3333338479        0.6400822952
END_POSITIONS
END_ENGINE_INPUT
END

 
Thank you for your suggestion in advances!


 
Best regards,

Clarence

Postdoctoral Fellow

City University of Hong Kong


 


 
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