[Pw_forum] Bad energetic of Li adsorbed graphene by DFT-D2 using QE

[Ari P Seitsonen]

Dear Saif Ullah,

   (Next time with your affiliation, please)

   I wonder why you have commented out the spin polarisation; did you do 
the same witht eh other codes? Since your system is neutral, it looks to 
me as if your system would have an odd number of electrons, but the spin 
polarisation is not accounted for. Did you check that your energies are 
well converged, considering that you are performing calculations 
with 'vc-relax'?

     Greetings from Sunny Paris,

        apsi

-=*=-=*=-=*=-=*=-=*=-=*=-=*=-=*=-=*=-=*=-=*=-=*=-=*=-=*=-=*=-=*=-=*=-=*=-=*=-
   Ari Paavo Seitsonen / Ari.P.Seitsonen at iki.fi / http://www.iki.fi/~apsi/
     Ecole Normale Supérieure (ENS), Département de Chimie, Paris
     Mobile (F) : +33 789 37 24 25    (CH) : +41 79 71 90 935


On Wed, 4 Oct 2017, Saif Ullah wrote:

> Dear QE users,
> I'm trying to reproduce the Li adsorbed graphene with DFT-D2 using QE. The adsorption energy is very much underestimated (-0.66 eV/Li) as
> compared to the values found in the literature. My SIESTA vdW-DF/DZP value is -1.11 eV/Li, pretty much in agreement with the literature. I have
> used different cutoff values with different pseudopotentials. I don't know where is the problem. Following is one of my inputs. Need your
> suggestions, please. Thanks
> 
> &CONTROL
>    calculation='vc-relax',
>   outdir='.',
>   prefix='calc',
>   pseudo_dir='.',
>   verbosity='high',
>  tstress=.true.
> tprnfor=.true.
> etot_conv_thr=1.0D-4
> forc_conv_thr=1.D-3
> wf_collect=.true.
> nstep=1000
> /
> 
> &SYSTEM
>   ibrav=0,
>   nat=51,
>   ntyp=2,
>   ecutwfc=40,
>   ecutrho=320,
>    input_dft='PBE',
>   occupations='smearing',
>   smearing='mp',
>   degauss=0.01d0,
>  vdw_corr='Grimme-D2',
> !  nspin=2,
> !  starting_magnetization(1)=0.7
> !  starting_magnetization(2)=0.6
> /
> 
> &ELECTRONS
>    diagonalization='cg',
>   conv_thr=1d-08,
>   mixing_mode='local-TF',
>   mixing_beta=0.500d0,
>  electron_maxstep=2000
> /
> &IONS
> ion_dynamics='bfgs'
> /
> &CELL
>    cell_dynamics = 'bfgs' ,
>   cell_dofree='2Dxy'
> /
> ATOMIC_SPECIES
> C 12.010700d0 C.pbe-van_ak.UPF
> Li  6.941000d0 Li.pbe-n-van.UPF 
> CELL_PARAMETERS (angstrom)
>   12.353060724   0.000889035  -0.201450000
>   -6.175669462  10.698563666   0.201310000
>   -0.000049454   0.000028549  20.000000000
> 
> ATOMIC_POSITIONS (angstrom)
> C       -0.123777599   0.044352021   0.750813339
> C        2.347139643   0.044536664   0.710530839
> C        4.816959818   0.046608474   0.671588196
> C        7.288030852   0.047974520   0.631371477
> C        9.759254756   0.046949526   0.590970165
> C       -1.361324273   2.182837743   0.784592128
> C        1.111661447   2.176898866   0.738849472
> C        3.584693057   2.183131578   0.703985603
> C        6.053702309   2.186196980   0.671658550
> C        8.522771292   2.186413475   0.631364175
> C       -2.598243992   4.325485482   0.824910219
> C       -0.131078480   4.322022349   0.764237921
> C        2.354133011   4.322141066   0.723759919
> C        4.821870209   4.325914119   0.703967494
> C        7.288439627   4.327051393   0.671562970
> C       -3.831089225   6.466525503   0.871657296
> C       -1.366959478   6.470638409   0.819586551
> C        1.111648295   6.474564682   0.764205441
> C        3.590771165   6.470877940   0.738791095
> C        6.055337825   6.467163164   0.710460311
> C       -5.064123742   8.605360424   0.914570582
> C       -2.595447017   8.606844025   0.871611006
> C       -0.124940436   8.609595937   0.824824937
> C        2.349153535   8.609719150   0.784488796
> C        4.820054590   8.607291549   0.750697179
> C       -0.125510159   1.469181337   0.757732918
> C        2.348583973   1.469399905   0.717413261
> C        4.819499832   1.472058312   0.683659878
> C        7.288388407   1.473415839   0.646082581
> C        9.757057163   1.472349661   0.603098319
> C       -1.367183927   3.608059861   0.792700719
> C        1.111411672   3.604765482   0.737260404
> C        3.590550668   3.608523771   0.711920217
> C        6.055141240   3.612373570   0.683651546
> C        8.521773207   3.612481509   0.643390074
> C       -2.598108408   5.752895502   0.838312859
> C       -0.130966528   5.757101185   0.777712574
> C        2.354245670   5.757343547   0.737229826
> C        4.822007602   5.753541812   0.717366687
> C        7.288591341   5.752608946   0.684948021
> C       -3.829804361   7.892507839   0.886438561
> C       -1.360854441   7.895696352   0.838263118
> C        1.112121068   7.902104754   0.792620096
> C        3.585162055   7.896134775   0.757637017
> C        6.054187493   7.893269674   0.725270353
> C        1.111459010  -0.667769729   0.725378109
> C        3.582681447  -0.666400412   0.685002360
> C        6.052708940  -0.664305301   0.643406933
> C        8.523624623  -0.664119335   0.603107212
> C       10.993446884  -0.665855193   0.564139854
> Li       1.142006551   5.022080560   2.622103194
> K_POINTS automatic
>  6 6 1 0 0 0
> 
>