Dear QE users,
I am currently in the process of learning how to model hydrogen adsorption on a
graphene sheet. So, as a starting point I tried to calculate the adsorption
energy of hydrogen on boron doped graphene. However, I am unable to obtain
values close to those that were stated in papers with similar DFT calculations.
Does anyone have any suggestions as to what I might be doing incorrectly? My
calculated value was -0.74 eV (please refer to below for input file used) while
other papers stated -0.014 eV. I've tried different orientations for the
hydrogen molecule (vertical vs horizontal to the graphene sheet) but my final
value doesn't change by much (~0.01eV).
&control
prefix='h2ads_BG'
calculation='relax'
outdir = './out'
pseudo_dir = '/scratch/Hydrogen_Adsorption/pseudo/'
forc_conv_thr=1D-3
/
&system
ibrav=0, nat=34, ntyp=3,
ecutwfc=25, ecutrho=200
occupations='smearing', smearing='methfessel-paxton', degauss=0.01
/
&electrons
mixing_mode='local-TF'
/
&ions
/
CELL_PARAMETERS
18.65816237 0.000000000 0.000000000
9.329081185 16.15844260 0.000000000
0.000000000 0.000000000 28.34588983
ATOMIC_SPECIES
C 12.01 C.pbe-van_bm.UPF
H 1.001 H.pbe-van_bm.UPF
B 10.81 B.pbe-n-van.UPF
ATOMIC_POSITIONS angstrom
C 1.728024 0.709000 0.001000
C 4.184072 0.709000 0.001000
C 6.640120 0.709000 0.001000
C 9.096169 0.709000 0.001000
C 1.728024 2.127000 0.001000
C 4.184072 2.127000 0.001000
C 6.640120 2.127000 0.001000
C 9.096169 2.127000 0.001000
C 2.931405 2.793323 0.001000
C 5.436735 2.793328 0.001000
C 7.892783 2.793323 0.001000
C 10.324192 2.793323 0.001000
C 2.956048 4.254000 0.001000
C 5.412096 4.254000 0.001000
B 7.868144 4.254000 0.001000
H 7.483935 4.254000 1.220000
H 8.252353 4.254000 1.220000
C 10.324192 4.254000 0.001000
C 4.184072 4.963000 0.001000
C 6.640120 4.963000 0.001000
C 9.096169 4.963000 0.001000
C 11.601494 4.963000 0.001000
C 4.184072 6.381000 0.001000
C 6.640120 6.381000 0.001000
C 9.096169 6.381000 0.001000
C 11.601494 6.381000 0.001000
C 5.412096 7.090000 0.001000
C 7.868144 7.090000 0.001000
C 10.373470 7.090000 0.001000
C 12.829518 7.090000 0.001000
C 5.412096 8.508000 0.001000
C 7.868144 8.508000 0.001000
C 10.373470 8.508000 0.001000
C 12.829518 8.508000 0.001000
K_POINTS automatic
5 5 1 1 1 1
Thank you all in advance.
Regards,
Janet Wong
Graduate Student
University of Toronto
Canada
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