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<DIV><FONT face=Verdana size=2>Dear all:</FONT></DIV>
<DIV style="TEXT-INDENT: 2em">I have used PWscf to do atomic position relaxition
under finite electric field. The electric field is applied by adding a saw-like
potential to bare ionic potential. The total force calculated seems not to be
convergent. And there are two questions unclear for me:</DIV>
<DIV style="TEXT-INDENT: 2em">1. In atomic position relaxition, does the
force from external electric field contribute to total force?</DIV>
<DIV style="TEXT-INDENT: 2em">2. Will all the atoms move along the direction of
external electric field as a whole? If that happens, the total energy and total
force can not get convergence.</DIV>
<DIV style="TEXT-INDENT: 2em"> </DIV>
<DIV style="TEXT-INDENT: 2em">Thanks for your warmly help!</DIV>
<DIV style="TEXT-INDENT: 2em"> </DIV>
<DIV>Y.P.Wang</DIV>
<DIV><FONT face=Verdana size=2></FONT> </DIV>
<DIV align=left><FONT face=Verdana color=#c0c0c0 size=2>2009-06-30
</FONT></DIV><FONT face=Verdana size=2>
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<DIV><FONT face=Verdana color=#c0c0c0 size=2><SPAN>shypirate</SPAN>
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