Dear Yang <br>you can do relaxation with  calculation  = "relax", and<br><br> &electrons<br>       conv_thr = 1.d-6,<br>       startingwfc = 'atomic',<br>       mixing_beta = 0.3,<br>   diagonalization = 'david_overlap',<br>
/<br> &ions<br> ion_dynamics = 'damp',<br>  pot_extrapolation = "second_order",<br>  wfc_extrapolation = "second_order",<br><br> and also you can fix positions with '0' after any ATOMIC_POSITIONS<br>
bye Mansoureh<br><br><br><br><div class="gmail_quote">On Wed, Jul 9, 2008 at 7:22 PM, ΛοΡτ <<a href="mailto:sunyang198498@gmail.com">sunyang198498@gmail.com</a>> wrote:<br><blockquote class="gmail_quote" style="border-left: 1px solid rgb(204, 204, 204); margin: 0pt 0pt 0pt 0.8ex; padding-left: 1ex;">
Hi!<br>
how could I relax the atoms position without changing the cell parameters<br>
say, if i have a simple cubic cell with each point having a benzene<br>
structure. How could I relax the benzene's atoms, say, hydrogen and<br>
carbon with the fixed edge size within the simple cubic cell.<br>
<br>
Thank you,<br>
<br>
Yang<br>
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