<html><head><style type="text/css"><!-- DIV {margin:0px;} --></style></head><body><div style="font-family:times new roman,new york,times,serif;font-size:12pt">Dear Lorenzo<br>Thank you for reply. IF I change the value of 1.98 to 0.4 then it  should work or not? Do I choose bigger cell?Which parameter should be modified?<br>thanks<br><div> </div>Ali Kazempour<br><br><br><br><div><br>Fritz-Haber-Institut              fax   : ++49-30-8413 4701<br>der Max-Planck-Gesellschaft<br>Faradayweg 4-6                    e-mail: kazempou@fhi-berlin.mpg.de<br>D-14 195 Berlin-Dahlem / German<div><br></div><div style="font-family: times new roman,new york,times,serif; font-size: 12pt;"><br><div style="font-family: arial,helvetica,sans-serif; font-size: 13px;"><font size="2" face="Tahoma"><hr size="1"><b><span style="font-weight: bold;">From:</span></b> Lorenzo Paulatto <paulatto@sissa.it><br><b><span style="font-weight: bold;">To:</span></b> PWSCF Forum
 <pw_forum@pwscf.org><br><b><span style="font-weight: bold;">Sent:</span></b> Mon, November 9, 2009 2:39:17 PM<br><b><span style="font-weight: bold;">Subject:</span></b> Re: [Pw_forum] constraints<br></font><br>
In data 09 novembre 2009 alle ore 14:32:52, ali kazempour  <br><<a ymailto="mailto:kazempoor2000@yahoo.com" href="mailto:kazempoor2000@yahoo.com">kazempoor2000@yahoo.com</a>> ha scritto:<br><br>> Dear All<br>> I want to fix the distance between  two atom during relaxation , the  <br>> distance is 1.98 , but the code crash and the error is<br>>      target =   3.67419827<br>>      dmax   =   2.79062000<br>><br>>  %%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%<br>>      from init_constraint : error #         1<br>>      the target for constraint 1 is larger than the largest possible  <br>> value<br>>  %%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%<br>><br>> why does it happen and what can I do?<br><br>Dear Ali,<br>the
 constraint is in unit of celldm(1), in your specific case you have  <br>asked the two atoms to be about 16 Angstrom apart, which is impossible in  <br>periodic boundary conditions with such a unit cell.<br><br>best regards<br><br><br>-- <br>Lorenzo Paulatto<br>SISSA  &  DEMOCRITOS (Trieste)<br>phone: +39 040 3787 511<br>skype: paulatz<br><span>www:   <a target="_blank" href="http://people.sissa.it/%7Epaulatto/">http://people.sissa.it/~paulatto/</a></span><br><br>     *** save italian brains ***<br><span>  <a target="_blank" href="http://saveitalianbrains.wordpress.com/">http://saveitalianbrains.wordpress.com/</a></span><br>_______________________________________________<br>Pw_forum mailing list<br><a ymailto="mailto:Pw_forum@pwscf.org" href="mailto:Pw_forum@pwscf.org">Pw_forum@pwscf.org</a><br><span><a target="_blank"
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