<div dir="ltr"><div dir="ltr"><div class="gmail_default" style="font-family:georgia,serif">items in quote marks are interpreted as data type string by the computer, the error might be triggered by how you have written the prefix</div><div class="gmail_default" style="font-family:georgia,serif"><span style="font-family:Arial,Helvetica,sans-serif">&CONTROL</span><br style="font-family:Arial,Helvetica,sans-serif"><span style="font-family:Arial,Helvetica,sans-serif">   calculation      = 'relax'</span><br style="font-family:Arial,Helvetica,sans-serif"><span style="font-family:Arial,Helvetica,sans-serif">   restart_mode     = 'from_scratch'</span><br style="font-family:Arial,Helvetica,sans-serif"><span style="font-family:Arial,Helvetica,sans-serif">   nstep            = 999</span><br style="font-family:Arial,Helvetica,sans-serif"><span style="font-family:Arial,Helvetica,sans-serif">   tstress          = .false.</span><br style="font-family:Arial,Helvetica,sans-serif"><span style="font-family:Arial,Helvetica,sans-serif">   tprnfor          = .true.</span><br style="font-family:Arial,Helvetica,sans-serif"><span style="font-family:Arial,Helvetica,sans-serif">   outdir           = 'pw.dir'</span><br style="font-family:Arial,Helvetica,sans-serif"><span style="font-family:Arial,Helvetica,sans-serif">   prefix           = ?pw'</span><br style="font-family:Arial,Helvetica,sans-serif"><span style="font-family:Arial,Helvetica,sans-serif">   etot_conv_thr    = 1e-06</span><br style="font-family:Arial,Helvetica,sans-serif"><span style="font-family:Arial,Helvetica,sans-serif">   forc_conv_thr    = 0.001</span><br style="font-family:Arial,Helvetica,sans-serif"><span style="font-family:Arial,Helvetica,sans-serif">   trism            = .true.</span><br style="font-family:Arial,Helvetica,sans-serif"><span style="font-family:Arial,Helvetica,sans-serif">/</span><br></div><div class="gmail_default" style="font-family:georgia,serif"><span style="font-family:Arial,Helvetica,sans-serif"><br></span></div><div><div dir="ltr" class="gmail_signature"><div dir="ltr"><div dir="ltr"><div dir="ltr"><div dir="ltr"><div dir="ltr"><div dir="ltr"><div dir="ltr"><div style="font-size:12.8px"><div style="font-size:small"><b>Robinson J.  Musembi</b><br></div><div style="font-size:small"><span style="color:rgb(17,17,17);font-family:Roboto,Arial,sans-serif;font-size:14px">Solid State and Materials Research</span><span style="font-size:12.8px"><br></span></div><div style="font-size:small"><span style="font-size:12.8px">Department of Physics, University of Nairobi</span><br></div></div><div style="font-size:12.8px"><br></div><div style="font-size:12.8px"><br></div></div></div></div></div></div></div></div></div></div></div><img width="0" height="0" class="mailtrack-img" alt="" style="display:flex" src="https://mailtrack.io/trace/mail/7dfd805fdd9561971b5214ba55de7feddc0d5517.png?u=2771463"></div>

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<div style="font-family:Arial,Helvetica,sans-serif;font-size:1.3em"><font face="Verdana" size="1">------------------------------<wbr>-----------</font></div><div style="font-family:Arial,Helvetica,sans-serif;font-size:1.3em"><span style="font-family:Verdana;font-size:x-small">A KEBS 9001:2015 Certified Organization, No. KEBS/QMS/RF:064 Rev. 03</span><br></div><div style="font-family:Arial,Helvetica,sans-serif;font-size:1.3em"><span style="font-family:Verdana;font-size:x-small"><br></span></div>