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[okuno@osa.sci.jri.co.jp]

Dear Abinit Users.

I use Abinit for estimation of  the bond length of the HO-C length of the 
Graphite surface 
with its C atom is terminated by OH group, the distance between O atom of OH 
group and  
C atom of the graphite,  because Graghite in the solvant is always 
terminated by some functional group like OH.

We assume OH group density on the Graphite surface is very tiny, 
(we do not know this assumption is right), and set one sheet of Graphite 
in the unit  cell with 24 atoms and set OH group on the top of one Carbon 
atom. 

We calculate surface energy by E(Graphite + OH) -E(OH) -E(Graphite) 
(where E(x) is x's total energy) with changing the distance between  the 
Oxygen 
 and Carbon.

But the results shows the energy minimum of the surface energy is located the 
distance 6.5Bohr, and when the case of the distance 2.5Bohr (the distance of 
CH3-OH) the results show positive surface energy and indicate the OH group 
are not absorbed by Graphite. 

Are there some need for attention to treat the functional group like OH?


Our input file for the Graphite(one sheet with 24 atoms and one OH group)
is like below.



nsppol 2

#Definition of the unit cell
acell      13.9235010838      16.0774741976      25.3072104390
rprim     1.000000000000     0.000000000000     0.000000000000
          0.000000000000     1.000000000000     0.000000000000
          0.000000000000     0.000000000000     1.000000000000
ntypat    3 
znucl 1 6 8 
natom   26 
typat 2 2 2 2 2 2 2 2 2 2 2 2 2 2 2 2 2 2 2 2 2 2 2 2 3 1 
xcart 
    0.000000000000     0.000000000000     0.000000000000 
    2.320583513975     1.339789516470     0.000000000000 
    2.320583513975     4.019368549411     0.000000000000 
    0.000000000000     5.359158065882     0.000000000000 
    0.000000000000     8.038737098823     0.000000000000 
    2.320583513975     9.378526615293     0.000000000000 
    2.320583513975    12.058105648234     0.000000000000 
    0.000000000000    13.397895164704     0.000000000000 
    4.641167027950     0.000000000000     0.000000000000 
    6.961750541925     1.339789516470     0.000000000000 
    6.961750541925     4.019368549411     0.000000000000 
    4.641167027950     5.359158065882     0.000000000000 
    4.641167027950     8.038737098823     0.000000000000 
    6.961750541925     9.378526615293     0.000000000000 
    6.961750541925    12.058105648234     0.000000000000 
    4.641167027950    13.397895164704     0.000000000000 
    9.282334055900     0.000000000000     0.000000000000 
   11.602917569875     1.339789516470     0.000000000000 
   11.602917569875     4.019368549411     0.000000000000 
    9.282334055900     5.359158065882     0.000000000000 
    9.282334055900     8.038737098823     0.000000000000 
   11.602917569875     9.378526615293     0.000000000000 
   11.602917569875    12.058105648234     0.000000000000 
    9.282334055900    13.397895164704     0.000000000000 
    4.641167027950     5.359158065882     2.500000000000 
    4.641167027950     5.359158065882     4.500000000000 

tsmear 0.04 
kptopt 1
ngkpt 1 1 1 
ecut 60 
nstep 50 
toldfe 1.0d-6 



Y. OKuno 
Japan Research Institute.