<div>Dear All, </div>
<div>I also have calculated gamma phonon frequencies of anatase TiO2 .</div>
<div>I run ph.x caculation after relaxing the structure, but 9 of 18 frequencies are minus.</div>
<div> </div>
<div>Would you please give me some hints and help?</div>
<div> </div>
<div>input settings are below, thank you in advance !</div>
<div> </div>
<div><strong>phonons of TiO2 at Gamma<br> &inputph<br> tr2_ph=1.0d-14,<br> recover=.true.,<br> epsil=.true.,<br> prefix='tio2',<br> fildyn='TiO2-gamma.dyn',<br> outdir='/home/haiping/tmp/'<br> /<br>0.0 0.0 0.0</strong>
</div>
<div><strong></strong> </div>
<div><strong>Relaxing calculation input :</strong></div>
<div><strong>&CONTROL<br> title = 'TiO2' ,<br> calculation = 'relax',<br> verbosity = 'default',<br> tprnfor = .true.,<br> outdir = '/home/haiping/tmp/',<br> prefix = 'tio2',
<br> disk_io = 'default',<br> nstep = 200,<br> pseudo_dir = '/home/haiping/espresso/pseudo/',<br>/<br>&SYSTEM<br> ibrav= 14,<br> celldm(1)=10.2856,celldm(2)=1.0
,celldm(3)=1.0,<br> celldm(4)=-0.759357,celldm(5)=-0.759357,<br> celldm(6)=0.518714<br> nat = 6 ,<br> ntyp = 2 ,<br> nbnd = 30 ,<br> ecutwfc =
30.0000000000,<br> ecutrho = 160.000,<br> occupations = 'fixed' ,<br>/<br> </strong></div>
<p>&ELECTRONS<br> electron_maxstep = 100,<br> conv_thr = 1.0e-07,<br> mixing_mode = 'plain' ,<br> startingpot = 'atomic' ,<br> startingwfc = 'atomic' ,<br> mixing_beta = 0.300000000,
<br> mixing_ndim = 8,<br> diagonalization = 'david_overlap' ,<br> diago_david_ndim = 8,<br>/</p>
<p>&IONS<br> ion_dynamics = 'bfgs',<br> pot_extrapolation = 'first_order',<br> wfc_extrapolation = 'first_order',</p>
<p>/</p>
<p>ATOMIC_SPECIES<br></p>
<div>O 15.999 O.pw91-van_ak.UPF<br>Ti 47.867 Ti.pw91-nsp-van.UPF<br>ATOMIC_POSITIONS crystal<br>Ti 0.00000 0.00000 0.00000<br>Ti 0.75000 0.25000 0.50000<br>O 0.20800 0.20800 -0.00000<br>O 0.95800
0.45800 0.50000<br>O 0.54200 0.04200 0.50000<br>O 0.79200 0.79200 -0.00000<br>K_POINTS automatic<br>6 6 7 0 0 0<br><br><br><br> </div>
<div><span class="gmail_quote">On 8/19/06, <b class="gmail_sendername">Ezad Shojaee</b> <<a href="mailto:ezadshojaee@hotmail.com">ezadshojaee@hotmail.com</a>> wrote:</span>
<blockquote class="gmail_quote" style="PADDING-LEFT: 1ex; MARGIN: 0px 0px 0px 0.8ex; BORDER-LEFT: #ccc 1px solid">hi<br>i am trying to calculate phonon frequencies at gamma point of TiO2(anatase)<br>and i have relaxed the structure enough (i think )but performing
PH.X after<br>scf, 2of 18 frequencies are minus!<br>i want to know that what technical problem do i have? does anyone calculate<br>these beore?<br>any suggestion will be appreciated<br><br>_________________________________________________________________
<br>Express yourself instantly with MSN Messenger! Download today it's FREE!<br><a href="http://messenger.msn.click-url.com/go/onm00200471ave/direct/01/">http://messenger.msn.click-url.com/go/onm00200471ave/direct/01/</a>
<br><br>_______________________________________________<br>Pw_forum mailing list<br><a href="mailto:Pw_forum@pwscf.org">Pw_forum@pwscf.org</a><br><a href="http://www.democritos.it/mailman/listinfo/pw_forum">http://www.democritos.it/mailman/listinfo/pw_forum
</a><br></blockquote></div><br>