<div>dear all:</div>  <div>When optimizing lattice constant of the bulk graphite I met an error :</div>  <div>---------------------------------------------------<BR>from checkallsym : error #         3<BR>     not orthogonal operation<BR>---------------------------------------------------<BR>What is the reason? How to resolve it?</div>  <div>any help will be appreciated</div>  <div>NiuLi<BR>=================================================<BR>my input as follows:</div>  <div>cat > graphite.vcrx.in << EOF<BR>&CONTROL<BR>  calculation  = "vc-relax",<BR>  prefix       = "graphite",<BR>  pseudo_dir   = "$PSEUDO_DIR",<BR>  outdir       = "$TMP_DIR",<BR>  tstress = .true. ,<BR>  tprnfor = .true.
 ,<BR>                       nstep = 65 ,<BR>               etot_conv_thr = 1.0E-4 ,<BR>               forc_conv_thr = 1.0D-3 ,<BR>                          dt = 100 ,<BR>/<BR>&SYSTEM<BR>    ibrav = 4, <BR>    celldm(1) =4.6336, <BR>    celldm(3)=2.7243,<BR>    nat= 4, ntyp= 1,<BR>    ecutwfc =40  <BR>/<BR>&ELECTRONS<BR>  diagonalization = 'cg',<BR>  conv_thr    = 1.D-9,<BR>  mixing_beta = 0.7D0,<BR>/<BR>&IONS<BR>  pot_extrapolation = "second_order",<BR>  wfc_extrapolation =
 "second_order",<BR>/<BR>&CELL<BR>               cell_dynamics = 'damp-w',<BR>                       press = 0.0 ,<BR>                       wmass = 0.010 ,<BR> /<BR>ATOMIC_SPECIES<BR> C   12.0107  C.pz-vbc.UPF</div>  <div>ATOMIC_POSITIONS {crystal}<BR> C  0.0000000 0.0000000 0.0000000 <BR> C  0.0000000 0.0000000 0.5000000<BR> C  0.6666667 0.3333333 0.0000000<BR> C  0.3333333 0.6666667 0.5000000<BR>K_POINTS automatic<BR>4 4 4 1 1 1</div>  <div>EOF<BR>$ECHO " optimizing the lattice constant for bulk graphite...\c"<BR>$PW_COMMAND < graphite.vcrx.in > graphite.vcrx.out<BR>$ECHO " done"<BR></div><p>
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