<html><body><div style="color:#000; background-color:#fff; font-family:Arabic Transparent, Arial;font-size:12pt"><DIV style="RIGHT: auto" dir=ltr><STRONG style="RIGHT: auto">Dear Xirainbow</STRONG></DIV>
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<DIV style="RIGHT: auto" dir=ltr>thank alot for your respond. </DIV>
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<DIV style="RIGHT: auto" dir=ltr>I search in the input file of pwscf and saw that the is applied for a vc-relax calculation.</DIV>
<DIV style="RIGHT: auto" dir=ltr>can i use of <STRONG>press_conv_thr</STRONG> for a <STRONG>relax</STRONG> of phonon calculation?</DIV>
<DIV style="RIGHT: auto" dir=ltr>and why the stress on my system is too high?(-40kbar)</DIV>
<DIV style="RIGHT: auto" dir=ltr><SPAN style="RIGHT: auto" id=result_box lang=en closure_uid_834536629="46" a="undefined" c="4" sd="null"><SPAN class=hps closure_uid_834536629="239" sd="null">What</SPAN> <SPAN class=hps closure_uid_834536629="240" sd="null">parameters</SPAN> <SPAN class=hps closure_uid_834536629="241" sd="null">do</SPAN> <SPAN class=hps closure_uid_834536629="242" sd="null">I</SPAN> <SPAN class=hps closure_uid_834536629="243" sd="null">need to be</SPAN> <SPAN class=hps closure_uid_834536629="244" sd="null">changed</SPAN> <SPAN class=hps closure_uid_834536629="245" sd="null">to</SPAN> <SPAN class=hps closure_uid_834536629="246" sd="null">reduce</SPAN> <SPAN style="RIGHT: auto" class=hps closure_uid_834536629="247" sd="null">stress?</SPAN></SPAN></DIV>
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<DIV style="RIGHT: auto" dir=ltr>Dear Banafshe Noori :<BR></DIV>
<DIV style="RIGHT: auto" dir=ltr> press_conv_thr is the parameter to control the final stress.<BR></DIV>
<DIV dir=ltr> The default value for press_conv_thr is 0.5D0 Kbar, which<BR></DIV>
<DIV dir=ltr>is good enough for most condition.<BR></DIV>
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<DIV dir=ltr>On Sat, Jun 1, 2013 at 11:45 PM, Banafshe Noori <<A href="mailto:b_noori88@yahoo.com" ymailto="mailto:b_noori88@yahoo.com"><FONT color=#2862c5>b_noori88@yahoo.com</FONT></A>> wrote:<BR></DIV>
<DIV style="RIGHT: auto" dir=ltr>> Dear all<BR></DIV>
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<DIV dir=ltr>> I want to calculate phonon frequency. I did a relax for my system(carbon<BR></DIV>
<DIV dir=ltr>> nanotube) and saw that the stress (Kbar) for this system is around<BR></DIV>
<DIV dir=ltr>> (-40Kbar). How can i decrease the stress on my system, and for an acceptable<BR></DIV>
<DIV dir=ltr>> magnitude of ferquencey, how much be the stress on system.?<BR></DIV>
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