<html><head><meta http-equiv=Content-Type content="text/html; charset=utf-8"><META name="Author" content="Novell GroupWise WebAccess"></head><body style='font-family: Tahoma, sans-serif; font-size: 13px; '>Dear Layla Martin-Samos,<br><br>Just a note: <br><br>vc-relax with cell_dofree='2Dshape' should be run with press=0D0 in the input file. Either the user must know this else the following can be placed in input.f90 to force the requirement.<br><br>Insert after <br>CALL init_dofree ( cell_dofree ) <br>on line 1424 the following code:<br><br>if(cell_dofree.eq.'2Dshape') press_ = 0d0<br><br>Regards<br><br>Richard Charles Andrew<br><br><br/><div style='clear: both;'>Postgraduate Student<br>Physics Department<br>University of Pretoria<br>South Africa</div><br/>>>> Layla Martin-Samos <lmartinsamos@gmail.com> 08/31/12 2:41 PM >>><br>
DEar Richard, thank you very much for your contribution. We will insert it in the trunk as soon as possible.<br><br>best regards<br><br>Layla<br><br><div class="gmail_quote">2012/8/31 Richard Andrew <span dir="ltr"><<a href="mailto:Richard.Andrew@up.ac.za" target="_blank">Richard.Andrew@up.ac.za</a>></span><br>
<blockquote class="gmail_quote" style="margin:0 0 0 .8ex;border-left:1px #ccc solid;padding-left:1ex"><div style="font-family:Tahoma,sans-serif;font-size:13px">
Dear QE team,<br><br>You requested we send any code additions we may have. I work in 2D systems and I noticed most DFT codes have no way for you to relax the 2D cell shape while keeping the area constant. The cell_dofree='shape' option in QE relaxes all degrees of freedom for the cell shape at constant volume which for 2D systems means also changing the vacuum layer. I have modified the cell_base.f90 module to include a cell_dofree='2Dshape' option which will relax the in-plane (xy plane) cell shape while keeping the area (therefore the vacuum layer) constant. This also required a change in the deviatoric.f90 code in the flib. Please find attached these modified files for your consideration. All modifications are marked between '! RICHARD' comment lines.<br>
<br>I also included in cell_base.f90 a cell_dofree='2Dxy' option where the xy plane is truly free as you had suggested in your code comment for cell_dofree='xy'.<br><br>Regards,<br><br>Richard Charles Andrew<br>
<br><div style="clear:both">Postgraduate Student<br>Physics Department<br>University of Pretoria<br>South Africa</div><br></div>
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