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Through the relaxation of a oxygen molecule on a surface by QE4.2,
it dissociated and adsorbed on the surface. The scf energy of each
step has decreased in compared with the previous step until the
relaxation completed. Now, can one say that there is not any TS for
O2 dissociation here ? <br>
<br>
Probably not. The potential energy surface might be not very
corrugated and the energy barrier for the dissociation might be not
very large, so that the dissociation of O2 could happen in a relax
calculation. I think there might be a very minute TS in the
dissociation process.<br>
<br>
Or is the reaction spontaneous ? <br>
<br>
If the total energy of system goes down continuously and the
adsorption energy of dissociated state is lower than the one of
molecular state, you could say the reaction is favorable. Whether it
is spontaneous, it is depend on how large of the energy barrier.<br>
<br>
<br>
If there was a TS in this procedure (dissociation and adsorption of
O2) would the optimization algorithm of QE4.2 stop the work or
continue ? <br>
<br>
If there is only one bond broken in the process you considered, you
could try constrained optimization technique. For you information,
please refer to B.Hammer (Hammer, B.; Jacobsen, K. W.; Norskov, J.
K. Phys. Rev. Lett. 1992, 69, 1971) or PJ Hu's work. (Alavi, A.; Hu,
P.; Deutsch, T.; Silvestrelli, P. L.; Hutter, J. Phys. Rev. Lett.
1998, 80, 3650). Or recent developed method by ZP Liu (J. Chem.
Theory Comput. 2010, 6, 1136–1144 )<br>
<br>
hope helps,<br>
<br>
best<br>
<br>
vega<br>
On 09/29/10 22:59, Masoud Nahali wrote:
<blockquote
cite="mid:AANLkTinJA=yo0fppvD5Dmt3LruWYiMiyX6bGEzEz+GT3@mail.gmail.com"
type="cite"><br clear="all">
<div> Dear PWscf Users<br>
<br>
Through the relaxation of a oxygen molecule on a surface by
QE4.2, it dissociated and adsorbed on the surface. The scf
energy of each step has decreased in compared with the previous
step until the relaxation completed. Now, can one say that there
is not any TS for O2 dissociation here ? Or is the reaction
spontaneous ? If there was a TS in this procedure (dissociation
and adsorption of O2) would the optimization algorithm of QE4.2
stop the work or continue ? Any help would be <strong
style="font-weight: normal;">appreciate</strong>. Many Thanks
<br>
</div>
<div> </div>
<div> </div>
<div><i><font color="#000066" face="comic sans ms,sans-serif">-----------------</font></i></div>
<div><i><font color="#000066" face="comic sans ms,sans-serif">Masoud
Nahali</font></i></div>
<div><font size="1"><font face="times new roman,serif"><font
size="2"><i><font size="1"><font face="times new
roman,serif"><font size="2"><i>PhD Student of
Physical Chemistry<br>
Sharif University of Technology</i> <br>
</font></font></font> <br>
</i></font></font></font></div>
<br>
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<br>
<div class="moz-signature">-- <br>
<p><font color="black">
================================================<br>
Vega Lew ( weijia liu)<br>
Graduate student<br>
State Key Laboratory of Materials-oriented Chemical
Engineering<br>
Nanjing University of Technology, 210009, Nanjing, China<br>
***************************************************************<br>
Email: <a class="moz-txt-link-abbreviated" href="mailto:vegalew@gmail.com">vegalew@gmail.com</a><br>
Office: Room A705, Technical Innovation Building,<br>
Xinmofan Road 5#, Nanjing, China<br>
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