Dear Sandeep, the following input works pretty well: &CELL_OPT EXTERNAL_PRESSURE 1.0 0.0 0.0 0.0 1.0 0.0 0.0 0.0 1.0 PRESSURE_TOLERANCE 0.1 OPTIMIZER cg KEEP_ANGLES true &CG &LINE_SEARCH TYPE 2pnt &END LINE_SEARCH &END CG &END CELL_OPT Of course, you can optimize the angles, too, by setting "KEEP_ANGLES false". Pressure tensor and pressure tolerance are system dependendent. Best regards, Andreas Am Mittwoch, 28. März 2012 11:11:28 UTC+2 schrieb sandeep:<blockquote class="gmail_quote" style="margin: 0;margin-left: 0.8ex;border-left: 1px #ccc solid;padding-left: 1ex;">Dear all, I would like to perform cell optimization with no temperature using CP2K. I searched for this keyword in mailing list. I didn't find many useful posts in this regard. Since I am new to this type of calculation, can you suggest me few references where this method is used sucessfully ? How should i check the correct value of CUTOFF for my system to carry out this calculation? Any suggestions for carrying out this calculations are greatly appreciated. Thanks & Regards, Sandeep </blockquote>