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<P style="MARGIN: 0cm 0cm 0pt" class=MsoNormal><FONT size=3
face="Times New Roman">Dear QE users</FONT></P>
<P style="MARGIN: 0cm 0cm 0pt" class=MsoNormal><?xml:namespace prefix = o ns =
"urn:schemas-microsoft-com:office:office" /><o:p><FONT size=3
face="Times New Roman"> </FONT></o:p></P>
<P style="MARGIN: 0cm 0cm 0pt" class=MsoNormal><FONT size=3
face="Times New Roman">I want to model adsorption of a large molecule on a
relatively large slab. After test convergence on the number of layers for clean
surface, I found 14 layers are needed, but for well-known technical reasons
(time and memory limitation), I am thinking on how can one take into account the
atoms of just some 3 topmost layers of the slab, and the effects of the
remaining layers of the slab as an external potential. </FONT></P>
<P style="MARGIN: 0cm 0cm 0pt" class=MsoNormal><FONT size=3
face="Times New Roman">Is it a meaningful question and what about its
feasibility in the context of QE?</FONT></P>
<P style="MARGIN: 0cm 0cm 0pt" class=MsoNormal><FONT size=3
face="Times New Roman">Thanks in advance.</FONT></P>
<P style="MARGIN: 0cm 0cm 0pt" class=MsoNormal><SPAN
style="mso-spacerun: yes"><FONT size=3
face="Times New Roman"></FONT></SPAN> </P>
<P style="MARGIN: 0cm 0cm 0pt" class=MsoNormal><o:p><FONT size=3
face="Times New Roman"> </FONT></o:p></P></FONT></DIV>
<DIV><FONT size=2
face=Arial>-------------------------------------------<BR>Yavar Taghipour<BR>PhD
Student<BR>Physics Group, AEOI<BR>Tehran-Iran</FONT></DIV>
<DIV> </DIV>
<DIV><FONT size=2 face=Arial>Email: <A
href="mailto:ytaghipour@aeoi.org.ir">ytaghipour@aeoi.org.ir</A><BR>Phone: +98
(0) 21
82064556<BR>-----------------------------------------------------------</FONT></DIV></BODY></HTML>