[Pw_forum] About energy of a single atom

[Shujun Hu]

Dear Isaev,
I mean I want to calculate the bond energy of O2 molecular, to test the PP, using
such methord followed:
E(single atom)*2-E(O2 molecular)=>E(bond)
, as E(single atom) including the energy of valence electrons only. The value of
E(single atom) can be obtained from the PP file as "totle energy". Right? The
biggest difficulty for me is obtaining the energy of O2 molecular under the
periodic boundary condition. You know the distance between O2 moleculars is much
larger than the bond length. How can i set up the value of celldm(1), celldm(2)...
in the pw.x calculating?
    Best wishes

                              Shujun Hu
____________________________
hushujun at mail.sdu.edu.cn